Class 10 Physics Chapter 7 Notes Kerala Syllabus Mechanical Advantage in Action Questions and Answers

The comprehensive approach in SCERT Kerala Syllabus 10th Standard Physics Textbook Solutions and Class 10 Physics Chapter 7 Mechanical Advantage in Action Notes Questions and Answers English Medium ensure conceptual clarity.

SSLC Physics Chapter 7 Notes Questions and Answers Pdf Mechanical Advantage in Action

SCERT Class 10 Physics Chapter 7 Mechanical Advantage in Action Notes Pdf

SSLC Physics Chapter 7 Questions and Answers – Let’s Assess

Question 1.
Write down an example of a lever where the load arm and effort arm are equal. What is its mechanical advantage?
Answer:
Common balance
Mechanical advantage = 1

Question 2.
In which order of lever is the load arm longer than the effort arm? Write down an example. Which may be the possible mechanical advantage? Choose from the brackets.
(less than one/one/more than one)
Answer:
Third order of lever
Example: ice tongs
less than one

Question 3.
As shown in the figure, an object is suspended from one end of a meter scale. When 400 gwt is suspended from the midpoint of the other side, the scale is balanced. What is the mass of the object? What is the weight of the object?

Answer:
Load = x
Load arm = 50 cm
Effort = 400 gwt
Effort arm = 25 cm
\(\frac{\text { Load }}{\text { Effort }}\) = \(\frac{\text { Effort arm }}{\text { Load arm }}\)
\(\frac{x}{400}\) = \(\frac{25}{50}\)
x = 200 gwt
Mass of the object = 200 g
Weight of the object = 200 gwt

Question 4.
In which type of lever is the mechanical advantage always greater than one?
Answer:
Second order lever

Question 5.
Draw a schematic diagram of a second order lever. Mark the fulcrum, load, and effort. Explain why the mechanical advantage of this is neither one nor less than one.
Answer:

Mechanical advantage = \(\frac{\text { Effort arm }}{\text { Load arm }}\)
As the load comes in between the fulcrum and effort, the effort arm will always be greater than the load arm. So the mechanical advantage of a second order lever is neither one nor less than one.

Question 6.
A log weighing 5000 kgwt is lifted through a height of 2 m onto a lorry using an inclined plane. A force of 2000 N was applied. What is the length of the inclined plane used to lift the log? What is the mechanical advantage in this situation? (Consider g = 10 m/s²)
Answer:
Mechanical advantage of an inclined plane, MA
= (L/E) = (l\h)
L = Load = 5000 kgwt = 5000 ×
10 N = 50000 N
E = Effort = 2000 N
Mechanical advantage = \(\frac{L}{E}\) = \(\frac{50000}{2000}\) = 25
l/h = 25
h = 2 m
Length of the inclined plane, = 2 × 25 = 50 m

Question 7.
How will you calculate the mechanical advantage of a screw? Describe an experiment to prove that a screw is an inclined plane.
Answer:
Mechanical advantage of a screw
=length of one thread /pitch Cut a paper in the shape of an inclined plane. Colour its slanting edge as in Fig.7.35(a)
Wrap this paper around a cylindrical pencil as in Fig.7.35(b).
We can see the coloured lines that appear as rings on the pencil look,like a screw.

Question 8.
A load of 1600 kgwt is suspended from an axle with a diameter of 6 cm. What should be the force applied in newton, to turn a 3 m long lever on one side of the axle, to lift this load? (Consider g = 10 m/s²)
Answer:
Mechanical advantage of axle and wheel = \(\frac{R}{r}\) = \(\frac{L}{E}\)
Diameter of the axle = 6 cm
Radius of the axle, r = 3 cm
Load = L = 1600 kgwt
= 1600 × 10 N
= 16000 N
\(\frac{L}{E}\) = \(\frac{R}{r}\)
\(\frac{16000}{E}\) = \(\frac{1}{2}\)
Effort, E = 160 N

Question 9.
Explain the necessity of gears in vehicles.
Answer:
While going uphill, large wheel is connected to the toothed wheel attached to the engine. When connected to a large toothed wheel, the speed of the vehicle decreases, but its efficiency to rotate increases.

To increase the speed of the vehicle, the toothed wheel attached to the engine must be connected to the small toothed wheel that helps to turn the tyre of the vehicle.

Question 10.
Match appropriately.

Lever	A	B	C
First order	Load is always more than the effort	Fulcrum comes in between effort and load	Mechanical advantage is always less than one
Second order	Load can be equal to, lesser or greater than the effort	Effort comes in between fulcrum and load	Mechanical advantage is always more than one
Third order	Load is always less than the effort	Load comes in between effort and fulcrum	Mechanical advantage is always equal to one or greater than one or lesser than one.

Answer:

Lever	A	B	C
First order	Load can be equal to, lesser or greater than the effort	Fulcrum comes in between effort and load	Mechanical advantage is equal to one or greater than one or lesser than one.
Second order	Load is always more than the effort	Load comes in between effort and fulcrum	Mechanical advantage is always more than one
Third order	Load is always less than the effort	Effort comes in between fulcrum and load	Mechanical advantage is always less than one

Physics Class 10 Chapter 7 Notes Kerala Syllabus Mechanical Advantage in Action

Question 1.
Observe the pictures given below. Name the simple machines shown in the pictures.


Answer:
Fig.7.1 (a) – Ramp as inclined plane
Fig.7.1 (b) – Spoon
Fig.7.1 (c) – Nail cutter
Fig.7.1 (d) – Bottle opener
Fig.7.1 (e) – Lever in the pump

Question 2.
How did these devices alleviate exertion?
Answer:
These devices reduce exertion by using simple machines (such as pumps, levers, and wedges) to change force or change its direction and thus helps to complete the task easily.

Question 3.
Observe the pictures. Analyse the situations in which a nail is pulled out.

a) In which situation [Fig. 7.2 (a), Fig. 7.2 (b)] was more force applied?
Answer:
In Fig. 7.2 (a)

b) Which device helped to increase the effect of the force we applied many folds?
Answer:
Nail puller

Question 4.
Observe the two ways of drawing water from a well.

a) In both the situations [Fig. 7.3(a), Fig. 7.3 (b)], is the force applied in the same direction?
Answer:
No, the force applied is not in the same direction in both situations.

b) In which direction is it more convenient to apply force?
Answer:
It more convenient to apply force in the downward direction as in situations in Fig. 7.3(b)

c) What is the benefit of using a pulley?
Answer:
Pulley helps to change the applied force in a more convenient direction, that is in the downward direction.

Question 5.
Analyse the situations in Fig. 7.2(a), Fig. 7.2(b) and Fig. 7.3(a), Fig. 7.3(b). Answer the questions given below.


a) In which situation did the effect of the force we applied increase many fold?
Answer:
In Fig. 7.2(b) and Fig. 7.3(b)

b) Which device increased the effect of the applied force many fold?
Answer:
Nail puller

c) Which device helped to change the direction of the applied force?
Answer:
Pulley

Advantages of using simple machines.

• Changes the magnitude of the effect of the force,
• Changes the direction of the applied force.

Simple machines are devices that change the magnitude of the effect offorce or the direction of the force or both.

Question 6.
How many types of simple machines are there? What are they?
Answer:
There are mainly six types of simple machines.
They are:

1. Lever
2. Pulley
3. Wheel and axle
4. Inclined plane
5. Screw
6. Wedge

Question 7.
When we squeeze a lemon using lemon squeezer,

a) What is the force we apply on the lemon squeezer?
(F₁/F₂)
Answer:
F₁

b) What is the force the lemon applies against the force we apply? (F₁/ F₂)
Answer:
F₂

When a lemon squeezer is used as a simple machine, the force we apply to squeeze the lemon is the effort. The force the lemon applies is the load.

The force we apply to a simple machine is the effort (E). The force the simple machine has to overcome is the load (L).

Question 8.
Identify the load and the effort while removing a nail using a nail puller [Fig. 7.2 (b)]. Note them down in your science diary.

Answer:
The force we apply to the nail puller is the effort (E).
The force the nail applies to the nail puller is the load (L).

Question 9.
Observe the picture of lifting a stone weighing 400 N, using a crowbar.

a) What is the weight lifted using the crowbar?
Ans:
400 N

b) What is the magnitude of force applied?
Answer:
100 N

c) How many times did the effect of the force applied increase?
Answer:
Four times

d) What is the advantage of using a crowbar?
Answer:
The effect of the force applied increased four times. That is the effect of the effort is increased by four times.

Question 10.
If a simple machine can lift a load four times the effort,
a) What is the ratio between the load and the effort?
Answer:
The ratio between the load and the effort is four.

b) How much is the mechanical advantage in the above case?
Answer:
mechanical advantage in the above case is four.

c) How many times did the effect of the force applied increase?
Answer:
Here the effect of the effort is increased by four times.

Mechanical advantage (MA) is the ratio of the load to the effort. It is a number indicating how many times of the load is the effort. Mechanical advantage is only a ratio. It has no unit Mechanical advantage, MA = \(\frac{\text { Load }}{\text { Effort }}\)

Question 11.
A force of 40 N was applied on a nail puller to pull a nail. If the mechanical advantage of the nail puller was three, what would be the load applied by the nail?
Answer:
Mechanical advantage = \(\frac{\text { Load }}{\text { Effort }}\)
Mechanical advantage = 3
Effort = 40 N
Load = ?
Load = Mechanical advantage × Effort
= 3 × 40 N
= 120 N

LEVER
Question 12.
Observe figure.

a) Name the position that supports the rod used as the simple machine.
(effort, load, fulcrum)
Answer:
fulcrum

b) Where is the fulcrum in common balance, seesaw, etc.?

Answer:
In the middle

Question 13.
A crowbar, beam of a common balance, seesaw, etc., are rigid rods. In all these, where is the load and effort?
Answer:
In crowbar, beam of a common balance, seesaw, etc., load is at one end and effort at the other end.

A lever is a rigid rod that can rotate around a fixed point called fulcrum.

Question 14.
What is the load arm here?
Answer:
The load arm here is 25 cm.

Question 15.
What is the perpendicular distance from the effort to the fulcrum known as?
Answer:
The perpendicular distance from the effort to the fulcrum known as the effort arm.

Question 16.
How much is the effort arm here?
Answer:
The effort arm here is 25 cm.

Question 17.
Change the loads and their positions and use appropriate efforts to bring the meter scale to equilibrium. Complete the table with the data obtained in each case.

Answer:

Question 18.
What inference can you arrive at from these activities?
Answer:
The inference that can be arrived at is that when a lever is in equilibrium, Load × Load arm = Effort × Effort arm.

When a lever is in equilibrium, Load × Load arm = Effort × Effort arm. This is the principle of a lever.

Question 19.
How can we calculate the mechanical advantage of a lever?
Answer:
Mechanical advantage = \(\frac{\text { Load }}{\text { Effort }}\)
According to the principle of the lever,
Load × Load arm = Effort × Effort arm
\(\frac{\text { Load }}{\text { Effort }}\) = \(\frac{\text { Effort arm }}{\text { Load arm }}\)
Mechanical advantage of levers = \(\frac{\text { Effort arm }}{\text { Load arm }}\)

Question 20.
You are given a meter scale, weights, a stand, a thread, and a mango. Find out and present how to
determine the mass of the mango.
Answer:
Suspend a meter scale at the centre of gravity. Suspend the mango at a fixed distance from that point. On the opposite side, at the same distance from the pivot, suspend the required weight to balance it. That will be the weight of the mango.

Question 21.
Is the fulcrum in a lever always between the load and the effort?
Answer:
No

Levers can be classified into three types based on the relative positions of the fulcrum, effort, and load. * First Order Lever * Second Order Lever * Third Order Lever

First Order Lever
Question 22.
Observe figure 7.11(a). What is the position of the fulcrum?

Answer:
The position of the fulcrum is in between the load and the effort.
First order lever

If the fulcrum is in between the load and the effort, it is a first order lever.Examples: common balance, scissors, seesaw.

Question 23.
In a common balance, the effort arm and the load arm are(equal/not equal).
Answer:
equal
Hence the load and effort will be equal.

Question 24.
What about while using scissors?
Answer:
In scissors the effort arm and load arm can vary depending on the use of the scissors.

Question 25.
While using a crowbar to move a stone, as shown in figure 7.11 (a), should you increase the effort arm or the load arm to enhance the mechanical advantage?
Answer:
While using a crowbar to move a stone, we should increase the effort arm to enhance the mechanical advantage.

Question 26.
What is the mechanical advantage in this case? (greater than one, one, less than one)
Answer:
greater than one

Question 27.
If the length of the load arm is increased more than the length of the effort arm, what will the mechanical advantage be?
(greater than one, one, less than one)
Answer:
less than one

Question 28.
Complete table 7.2 with the appropriate terms from the brackets.
(load is more than the effort, load and effort are equal, load is less than the effort)

Answer:

If the mechanical advantage is less than one	load is more than the effort
If the mechanical advantage is one	load and effort are equal
If the mechanical advantage is greater than one.	load is less than the effort

Question 29.
Write down examples for first order levers from daily life situations.
Answer:
Fixed pulley, common balance, scissors, seesaw, pliers, human elbow

Second Order Lever
Question 30.
Observe figure 7.13

a) Mark the position of the load, fulcrum, and effort in the figure.
Answer:

b) Where is the position of the load in the figure?
Answer:
The load comes in between the effort and the fulcrum

If the load comes in between the effort and the fulcrum, it is a second order lever. Examples: Lemon squeezer, nut cracker, bottle opener, staplers, wheelbarrows

Question 31.
Mark the load, fulcrum, and effort in the pictures given below.

Answer:

Question 32.
Where will the fulcrum in a second order lever be?
Answer:
At one end

Question 33.
What about the position of the load?
Answer:
The load comes in between the effort and the fulcrum.

Question 34.
Which of the following is correct in a second order lever?
(effort arm and load arm are equal, effort arm is longer than the load arm, effort arm is shorter than the load arm)
Answer:
Effort arm is longer than the load arm

Question 35.
The mechanical advantage of second order levers will always be
(less than one, one, greater than one)
Answer:
greater than one

Question 36.
Write down more examples for second order lever from daily life situations.
Answer:
Lemon squeezer, nut cracker, bottle opener, staplers, wheelbarrows

Third Order Lever
Question 37.
Observe figure 7.16 and mark the load, effort, and fulcrum.

Answer:

If the effort comes in between the load and the fulcrum, it is a third order lever. Examples: Tools used to pick sweets in bakeries, forceps, Tongs

Question 38.
In third order levers, which arm is longer?
(load arm, effort arm)
Answer:
load arm

Question 39.
What will be the mechanical advantage of a third order lever?
(less than one, one, greater than one)
Answer:
less than one

Question 40.
Write down more examples for third order levers from daily life situations.
Answer:

1. Fishing pole
2. Broom
3. ’ Tweezers
4. ’ Tools used to pick sweets in bakeries
5. ’ Forceps
6. ’ Tongs

Question 41.
The effort is greater than the load in a third order lever. If so, what is the advantage of using a third order lever?
Answer:
The advantage is that it helps to handle objects safely with ease.

Question 42.
Mark the fulcrum, load and effort in the case of a forceps.
Answer:

Question 43.
Complete the table

Answer:

Order of a lever	Relative position of fulcrum, load and effort	Mechanical advantage
First order	Fulcrum is in between the load and the effort	Greater than one /equal to one/less than one
Second order	Load is in between the fulcrum and the effort	Alwavs greater than one
Third order	Effort is in between the load and the fulcrum	Alwavs less than one

Fixed Pulley
Question 44.
What are fixed pulleys?
Answer:

Fixed pulleys are pulleys that rotate around a stationary axle. A fixed pulley can be imagined as many spokes rotating around a central pivot named fulcrum. In these spokes, the position where the load is experienced is marked as L and the position where the effort is applied is marked as E. In this, the effort arm and the load arm are the radii of the pulley.

Question 45.
What type of lever a fixed pulley is?
Answer:
A fixed pulley is similar to a first order lever.

Question 46.
What will be the relation between the load arm and the effort arm of the pulley?
(load arm is longer, effort arm is longer, effort arm and load arm are equal)
Ans:
effort arm and load arm are equal

Question 47.
When we consider a fixed pulley without friction, we have to apply …………………………
(more effort than the load, less effort than the load, an effort equal to load)
Answer:
an effort equal to load

Question 48.
What will be the mechanical advantage of a fixed pulley?
(less than one, one, greater than one)
Answer:
one

Question 49.
What is the advantage of using friction less fixed pulley to lift objects? Choose the correct option from those given below.
(can reduce the magnitude of the applied force / can change the direction of the applied force)
Answer:
can change the direction of the applied force

Question 50.
In a movable pulley the effort and the fulcrum are at either ends and the load is at the middle. Which is the order of this lever?
Answer:
Second order lever

Question 51.
Which is the load arm and effort arm?
Answer:
Load arm = Radius of the pulley
Effort arm = Diameter of the pulley

Question 52.
What is the mechanical advantage of a movable pulley?
Answer:
Mechanical advantage
= \(\frac{\text { Effort arm }}{\text { Load arm }}\) = \(\frac{\text { Diameter of the pulley }(2 r)}{\text { Radius of the pulley }(r)}[latex]
= 2

Question 53.
The mechanical advantage of a single movable pulley is 2. If so, how many times of the load to be lifted should the applied effort be?
Answer:
Half

Question 54.
The rope is pulled 2 m by applying effort. How much will the load rise?
Answer:
The load rises only one metre.

Question 55.
What should be the displacement of the rope, when the effort applied raises the load by 1 m?
(1 m, 2 m, 0 m)
Answer:
2 m

Question 56.
Is there a gain in work when the applied effort is halved? Prove.
Answer:
There is no gain in work when the applied effort is halved
Work, W = Fs
When the effort is reduced by half, the displacement produced by it is doubled.
That is, W = (F/2) × 2s = Fs. That is there is no change in the quantity of work done. No gain in work is achieved while using a movable pulley.

Question 57.
A movable pulley is used to lift 600 N load. When the rope is pulled 8 m by applying a force of 300 N then the load raises by 4 m. Prove that there is no gain in the work even though there is a gain in the effort applied.
Answer:
The displacement of the object, s = 4 m
Weight of the object, F = 600 N
Work done on the object
= F × s
= 600 × 4 = 2400 J
The displacement of the rope on applying 300 N force,
s₁ = 8 m
F₁ = 300N

The work done by the force we applied = F₁ s₁
= 30o × 8 = 2400 J
The work done on the object and the work done by the effort are equal.

Question 58.
Is there a gain in work by using simple machines?
Answer:
There is no gain in work by using simple machines.

Question 59.
The radius of the wheel is R and the radius of the axle is r. When the wheel is rotated once, What will be the distance moved by a point on the wheel’s circumference?
Answer:
When the wheel is rotated once, the distance moved by a point on the wheel’s circumference be 2πR.

Question 60.
What will be the distance moved by the object tied to the rope attached to the axle? (2πR / 2πr)
Answer:
2πr

Question 61.
What is the distance moved by the point on the wheel when rotated once due to the effort applied (E)?
Answer:
The distance moved by the point on the wheel when rotated once due to the effort applied (E) is 2πR.

Question 62.
What is the distance moved by the load?
Answer:
The distance moved by the load is 2πr.
The work done by the effort and the work done by the load are equal here.
Work done by the effort = Work done by the load
Work done = Fs
E × 2πR = L × 2πr
= L/E = R/r
Since the radius of the wheel is larger and the radius of the axle is smaller, the mechanical advantage of wheel and axle will be greater than one.
As the radius of the wheel increases, the mechanical advantage also increases.

• The train bogies were slowly lifted by turning the wheel using long levers.

Gear

Question 63.
What are gears? What are the uses of these gears?
Answer:
A gear is a mechanical device used in machines.
They are used to transfer motion or force from one part of the machine to another.

Question 64.
What is the main part of a gear system?
Answer:
The main part of a gear system is the system of two interlocking toothed wheels.
In gears, energy is transferred from a large toothed wheel to a small toothed wheel or from a small toothed wheel to a large toothed wheel.

Question 65.
When the large toothed wheel rotates once, how many times will the small toothed wheel rotate? (once, more than once, less than once)
Answer:
more than once

Question 66.
What changes will this cause in the speed of the second toothed wheel?
Answer:
The speed of the second toothed wrheel increases.

Question 67.
A toothed wheel is attached to the engine of most of the vehicles. What is the function of this toothed wheel?
Answer:
This toothed wheel is connected to a system of wheels of different sizes attached to the axle which transfers motion to the tyres.

Question 68.
Which wheel is connected to the toothed wheel attached to the engine to increase the speed of the vehicle?

To increase the speed of the vehicle, the toothed wheel attached to the engine must be connected to
the small toothed wheel that helps to turn the tyre of the vehicle.

Question 69.
Which wheel is connected to the toothed wheel attached to the engine while going uphill?
(small/large)

Answer:
large

Question 70.
What is the advantage of connecting the large wheel to the toothed wheel attached to the engine while going uphill?
Answer:
The speed of the vehicle decreases, but its efficiency to rotate increases.

Question 71.
What happens to the speed of the large toothed wheel when energy is transferred from the small toothed wheel to the large toothed wheel? (Increases/decreases)
Answer:
decreases

Question 72.
Try lifting the same object to the same height using inclined planes of different lengths. When did it feel easier?
Answer:
It felt easier when using inclined plane of more length.

Question 73.
An object is to be lifted to a height h metre by pushing along an inclined plane of length l metre. Here, what is the work done by the effort?
Answer:
If the effort is E and the load is L, then the work done by the effort E to move it over a distance,
l = (F_s) = El

Question 74.
An object is to be lifted to a height h metre by pushing along an inclined plane of length 1 metre.
Here, what is the work done by the load?
Answer:
Work done by the load L to lift to a height h is Work = Force × Displacement
i.e., Weight × height = Lh

Question 75.
An object is to be lifted to a height h metre by pushing along an inclined plane of length 1 metre. Here, what is the mechanical advantage?
Answer:

Question 76.
Does using a longer inclined plane or a shorter inclined plane provide more mechanical advantage?
Answer:
Mechanical advantage = [latex]\frac{\text { Length of inclined plane }}{\text { Height of inclined plane }}\)
So, using a longer inclined plane provides more mechanical advantage.

Question 77.
Inclined planes are often used in situations where objects are to be lifted.
a) What is the work done to lift a 600 N load by 3 m?
b) The force applied was 200 N along an inclined plane to lift this load. Displacement of the load was 9 m. What is the work done?
c) Is there a gain in the work done?
Answer:
a) Force, F = 600 N
Displacement, s = 3 m
Work done, W = Fs = 600 × 3 = 1800 Nm= 1800 J

b) Force, F = 200 N
Displacement, s = 9 m
Work done, W = Fs = 200 × 9 = 1800 Nm= 1800 J

c) There is no gain in work done.

Question 78.
What are the ways to increase the mechanical advantage of an inclined plane?
Answer:
We can increase the length of an inclined plane to increase the mechanical advantage.

Question 79.
Why are long inclined roads built in hairpin roads on ghats and other such places?


Answer:
The concept of mechanical advantage of inclined plane is utilised here. As we increase the length of an inclined plane the mechanical advantage increases. So the inclined roads are built with maximum length.
• It is understood that large heavy stones were taken up to build the pyramids using inclined roads.

Question 80.
Observe the wedges of different length and thickness. Which of these is easier to use? Why?

Answer:
Fig. 7.32 (c),

The wedge in figure 7.32 (c) has less thickness and more length. So, its mechanical advantage is greater than that of others. If a wedge is made longer and thinner, it will be easier to use.

Question 81.
Write down the use of a screw jack.
Answer:
A screw jack is used to lift vehicles to change a tyre or for minor repairs.

Question 82.
A 600 kgwt load is lifted by 4 m along an inclined plane of length 8 m. Calculate the mechanical advantage. What force must be applied along the inclined plane?
Answer:
Mechanical advantage of an inclined plane

Question 83.
Label the name of the simple machines given below.

Answer:

The bicycles and sewing machines we use today are often said to be the simplest machines. But they are a combination of many types of the simple machines mentioned above.

Std 10 Physics Chapter 7 Notes – Extended Activities

Question 1.
Plan a project to find the density of a meter scale.
Answer:
Find the centre of gravity of the meter scale. Hang the scale at a distance of 10 cm, 20 cm, 30 cm from the centre of gravity and determine the position required to balance it in each case.

Assuming the mass of the part that is 1 cm as m. Using the equation load × load arm = effort × effort arm, the mass of the scale and the density of it can be found out. When balancing it at 10 cm, the load = 60 × m
load arm = 30 cm
Effort = 40 × m + suspended mass (y)
load × load arm = 60 × m × 30
Effort × Effort arm = 40m × 20 + y × x (distance from the suspended mass ‘y’ to the fulcrum). Find the value of x, for a value of y (say 50 g or 100 g). Repeat the experiment by hanging the scale at different distances (as mentioned above 20 cm, 30 cm from the centre of gravity).
Solve for the mass from the euqation.
Find 100 × m = M, to find the total mass of the meter scale.

Measure the Length, breadth (b) and thickness (t) (dimensions) of the meter scale.
Calculate volume V= Length × Breadth × Thickness and calculate density using the formula
Density = \(\frac{M(\text { mass })}{V(\text { Volume })}\)

Question 2.
Observe a bicycle and list the simple machines that forms a part of it.
Answer:

1. Wheel and axle
2. Lever
3. Pulley
4. screw
5. Inclined plane

Mechanical Advantage in Action Class 10 Notes

Mechanical Advantage in Action Notes Pdf

• Devices that make exertion easier are called simple machines.
• Simple machines are devices that change the magnitude of the effect of force or the direction of the force or both.
• There are mainly six types of simple machines. They are:
  Lever, Pulley, Wheel and axle, Inclined plane, Screw and Wedge
• Mechanical advantage (MA) is the ratio of the load to the effort. It is a number indicating how many times of the load is the effort. Mechanical advantage is only a ratio. It has no unit.
  Mechanical advantage, MA = \(\frac{\text { Load }}{\text { Effort }}\)
• Centre of gravity is the point at which the entire weight of an object is considered to act.
• When a lever is in equilibrium, Load × Load arm = Effort × Effort arm. This is the principle of a lever.
• Levers can be classified into three types based on the relative positions of the fulcrum, effort, and load.
  • First Order Lever
  • Second Order Lever
  • Third Order Lever
• First order lever: In a first order lever, fulcrum comes in between effort and load. The mechanical advantage of a first order lever is equal to one or greater than one or lesser than one.
• Second order lever: The load comes in between effort . and fulcrum. Mechanical advantage of a second order . lever is always more than one.
• Third order lever: The effort comes in between fulcrum and load. Its mechanical advantage is always less than one.
• A Pulley is a simple machine. It is of two types:
  1. Fixed pulley
  2. Movable pulley
• In wheel and axle systems, the wheel is rotated by applying force (Effort) to it. When the wheel is rotated once, the axle also rotates once.
• Since the radius of the wheel is larger and the radius of the axle is smaller, the mechanical advantage of wheel and axle will be greater than one.
• A gear is a mechanical device used in machines. They are used to transfer motion or force from one part of the machine to another. The main part of a gear system is the system of two interlocking toothed wheels.
• A wedge is a double inclined plane.
• A screw jack is used to lift vehicles, to change a tyre or for minor repairs.

INTRODUCTION

Simple machines are basic mechanical devices that make work easier by changing the magnitude or direction of a force. Even the bicycles and sewing machines we use today are often said to be the simplest machines. Simple machines are the building blocks of more complex machines and have been used for centuries to perform tasks more efficiently. There are six classic simple machines. They are lever, pulley, wheel and axle, inclined plane screw and wedge. These machines operate on the principle of mechanical advantage, allowing a smaller force to move a larger load or perform tasks with less effort. They are fundamental in everyday tools and complex machinery, simplifying tasks like lifting, cutting, or moving objects. This unit deals with the basic ideas about simple machines.

Simple machines

• Devices that make exertion easier are called simple machines.
• Advantage of using simple machines.
  • Changes the magnitude of the effect of the force.
  • Changes the direction of the applied force.
• Simple machines are devices that change the magnitude of the effect of force or the direction of
  the force or both.
• There are mainly six types of simple machines. They are lever, pulley, wheel and axle, inclined plane, screw and wedge.
• The force we apply to a simple machine is the effort (E). The force the simple machine has to overcome is the load (L).
• Mechanical advantage (MA) is the ratio of the load to the effort. It is a number indicating how many times of the load is the effort. Mechanical advantage is only a ratio. It has no unit.

Mechanical advantage, MA = \(\frac{\text { Load }}{\text { Effort }}\)

Lever

• A lever is a rigid rod that can rotate around a fixed point called fulcrum.
• Centre of gravity is the point at which the entire weight of an object is considered to act.
• Levers can be classified into three types based on the relative positions of the fulcrum, effort, and load.
  • First Order Lever
  • Second Order Lever
  • Third Order Lever
• When a lever is in equilibrium,
  Load × Load arm = Effort × Effort arm. This is the principle of a lever.
  Mechanical advantage of levers = \(\frac{\text { Load }}{\text { Effort }}\) = \(\frac{\text { effort arm }}{\text { load arm }}\)
• If the fulcrum is in between the load and the effort, it is a first order lever.
  Examples: common balance, scissors, seesaw.
• The mechanical advantage of first order lever can be greater than one /equal to one/less than one.
• If the load comes in between the effort and the fulcrum, it is a second order lever. Examples: Lemon squeezer, nut cracker, bottle opener, wheelbarrows
• The mechanical advantage of second order levers will always be greater than one.
• If the effort comes in between the load and the fulcrum, it is a third order lever. Examples: Tools used to pick sweets in bakeries, forceps, Tongs
• The mechanical advantage of third order lever will be always less than order one.

Pulley

• Pulley is a simple machine. It is of two types. Fixed pulley and movable pulley.
• Fixed pulleys are pulleys that rotate around a stationary axle. A fixed pulley can be imagined as many spokes rotating around a central pivot named fulcrum. In these spokes, the position where the load is experienced is marked as L and the position where the effort is applied is marked as E. In this, the effort arm and the load arm are the radii of the pulley.
• Mechanical advantage of a fixed pulley is one
• When effort is applied on a movable pulley, the pulley and the load will be lifted upwards along the other side of the rope. This lifting is caused by the rotation of the pulley along the rope.
• Mechanical advantage of a movable pulley is 2 Mechanical advantage = \(\frac{\text { Diameter of the pulley (2r) }}{\text { Radius of the pulley (r) }}\)

Wheel and axle

• In wheel and axle systems, the wheel is rotated by applying force (Effort) to it. When the wheel is rotated once, the axle also rotates once. If the radius of the wheel is R and the radius of the axle is r, and when the wheel is rotated once, the distance moved by a point on the wheel’s circumference would be 2πR.
• Since the radius of the wheel is larger and the radius of the axle is smaller, the mechanical advantage of wheel and axle will be greater than one.
  Mechanical Advantage = \(\frac{\text { L(load) }}{\text { E (effort) }}\) = \(\frac{\text { Radius of wheel (R) }}{\text { Radius of axle (r) }}\)
• As the radius of the wheel increases, the mechanical advantage also increases
• A gear is a mechanical device used in machines. They are used to transfer motion or force from one part of the machine to another. The main part of a gear system is the system of two interlocking toothed wheels.

Inclined plane

• Mechanical advantage = \(\frac{\text { Length of inclined plane (l) }}{\text { Height of inclined plane(h) }}\)
• Using a longer inclined plane provides more mechanical advantage.

Wedge

• A wedge is a double inclined plane. Household tools like knife, axe, and work tools like chisel are variants of wedges.
• Mechanical advantage of a wedge \(\frac{\text { length of the inclined plane of the wedge }(l)}{\text { thickness of the wedge }(\mathrm{h})}\)

Screw

• A screw can be considered as an inclined plane. The distance between two consecutive threads is the pitch of a screw.
• The mechanical advantage of a screw = length of the inclined plane (l) / height of the inclined plane (h) = length of one thread (l) / pitch (h)

You may have seen loading a lorry using an inclined plane.
• When it is difficult to climb stairs, we use ramps. From this, it is understood that inclined planes are used to reduce exertion.
Devices that make exertion easier are called simple machines.

SIMPLE MACHINES
Let’s examine the ways in which simple machines make exertion easier.

TYPES OF SIMPLE MACHINES
LEVER
Activity to understand the principles related to levers
Suspend a wooden meter scale on a stand. Balance it as shown in figure 7.8.

Identify the point at which it is to be balanced.

Entire weight of the meter scale act through this point. This point is the centre of gravity of the meter scale. The meter scale can be suspended or pivoted along a perpendicular line passing through the centre of gravity as shown in the figure.

You can balance a book on the tin of your finger

A book can be balanced when it is pivoted on the perpendicular line passing through its centre of gravity.
Centre of gravity is the point at which the entire weight of an object is considered to act

Activity to understand the principles related to levers

Suspend a wooden meter scale along a perpendicular line passing through the centre of gravity as shown in the figure on a stand. Balance it as shown in figure. Suspend a mass of 50 g at a distance of 25 cm from the balancing point on one side of the meter scale. Suspend another mass of 50 g on the other side of the meter scale to balance it.

The weight suspended first is considered as the load. The perpendicular distance from the load to the fulcrum is the load arm. The weight suspended or the force applied to produce equilibrium in the rod is the effort.

PULLEY
A Pulley is a simple machine. It is of two types:
1. Fixed pulley
2. Movable pulley

Movable Pulley

When effort is applied on a movable pulley, the pulley and the load will be lifted upwards along the other side of the rope. This lifting is caused by the rotation of the pulley along the rope.

WHEEL AND AXLE
There were instances when modern machines failed to lift train bogies that had fallen into a lake. But they were brought ashore using a wheel and axle.

In wheel and axle systems, the wheel is rotated by applying force (Effort) to it. When the wheel is rotated once, the axle also rotates once.

INCLINED PLANE
You may have seen an inclined plane being used to load large logs, machine parts, etc., on to a lorry.

WEDGE
A wedge is a double inclined plane. Household tools like knife, axe, and work tools like chisel are variants of wedges.

SCREW JACK
A screw can be considered as an inclined plane. The distance between two consecutive threads is the pitch of a screw.

Activity to explain pitch of a screw.
Cut a paper in the shape of an inclined plane. Colour its slanting edge. (Fig 7.35(a))
Wrap this paper around a cylindrical pencil. (Fig.7.35(b))

The vertical distance from the beginning of the slanting edge of the paper (P) to where one full turn is completed (Q) is the pitch (h). That is, the distance between two consecutive threads is the pitch.

Activity to explain the length of one thread of a screw
Cut a paper in the shape of an inclined plane. Colour its slanting edge. (Fig.7.35(a))

Wrap this paper around a cylindrical pencil.(Fig.7.35(b)) Unwrap the paper and straighten it. Measure the distance from P to Q (Fig.7.35(c)). This Distance is the length of the thread PQ (l). That is the length of one thread of a screw.

The mechanical advantage of a screw = length of the inclined plane (l) / height of the inclined plane (h) = length of one thread (l) / pitch (h)