Kerala Syllabus Class 9 Physics Model Question Paper Set 5 English Medium

Teachers recommend solving Kerala Syllabus 9th Standard Physics Question Paper Set 5 to improve time management during exams.

Kerala Syllabus Std 9 Physics Model Question Paper Set 5 English Medium

Time: 1½ Hours
Max Score: 40 Marks

Instructions

• The first 15 minutes are given as cool-off time. This time is to be spent reading and understanding the questions.
• Answer the questions according to the directions.
• Score and time to be considered while answering.

I. Answer any three questions from 1 to 4. (1 score each) (3 × 1 = 3)

Question 1.
Speed of light in a medium having low optical density will be ______
Answer:
Greater

Question 2.
Write the equation of motion connecting velocity and time.
Answer:
v = u+at

Question 3.
As mass increases, inertia ______
Answer:
increases

Question 4.
As the distance from the Earth to the object increases, the force of attraction exerted by the Earth (increases/decreases)
Answer:
decreases

II. Answer any seven questions from 5 to 13. (2 score each) (7 × 2 = 14)

Question 5.
During summer season there seenis to be water logging on roads when viewed from a distance. What may be the reason?
Answer:
During summer season the layers of air closer to the road have a low optical density as it is warmer than the upper layers. The optical density of the air increases gradually as we go higher. When light rays coming from the surrounding objects pass through different layers of as with different optical densities. they undergo refraction and then total internal reflection. Such deviated light rays fall on our eyes. Hence their image appears to have formed on roads This phenomenon is known as mirage Such familiar images are usually seen on the surface of water That ‘s why water seems to be logged on roads wthen viewed from a distance.

Question 6.
Draw position. time graph

Time(s)	0	1	2	3	4
Position(m)	0	5	10	15	20

Answer:

Question 7.
Deflate a balloon and release it suddenly. What happens?
Answer:
Release of air causes the balloon to move in the opposite direction. Releasing air from the balloon is taken as action and the movement of the balloon is taken as reaction.

Question 8.
a)Which of the following figure represents the critical angle?

b) What do you mean by critical angle?
Answer:
a) Figure (5)
b) When a ray of light enters from an optically denser medium to a rarer medium, the angle of incidence at which the angle of refraction becomes 90° is the critical angle.

Question 9.
a) What Is meant by momentum?
b) Write down the equation for calculating momentum.
Answer:
a) The measurement of the quantity of motion of a body is called momentum.
b) Momentum p = mv

Question 10.
a) Define circular motion.
b) What is the relation between centripetal force and centripetal acceleration?
Answer:
a) The motion of an object through a circular path is said to be circular motion.
b) The force required to produce centripetal acceleration is centripetal force.

Question 11.
A car came to rest when brake was applied for 4s to get a retardation of 3m/s². Calculate how far the car would have travelled after applying the brake.
Answer:
a = -3 m/s² (retardation = negative acceleration) t = 4s
v = 0
v = u + at
-u = -3 × 4 + 0
u = 12 m/s
Displacement of the car,
s = ut + 1/2 at²
= (12 × 4) + (1/2) (-3) × 16
= 24 m

Question 12.
If a tennis ball (mass 58.5 g) and a cricket ball (mass 163 g) are to reach a certain distance when hit with a cricket bat, which is to be hit with greater force Why?
Answer:
The cricket ball. As mass increases, inertia also increase.

Question 13.
Suppose if the body is moved from the surface of the earth to the centre. What happens? Why?
Answer:
When it reaches the centre attractive force becomes zero. When a body is placed at the centre of the earth, it is attracted towards all directions. Therefore the resultant force of attraction at the centre is zero.

III. Answer any five questions from 14 to 19. ( 3 score each) (5 × 3 = 15)

Question 14.
Examine the graph and answer the following questions.

a) Is the motion of the object uniform/non uniform?
b) Say whether the acceleration from O to A is uniform? What about from A to B?
Answer:
a) Non- uniform
b) O→A : Uniform acceleration
A→B : Uniform retardation

Question 15.
a) Why does a freely falling body experience weightlessness?
b) Drill a hole at the bottom of an open bottle and fill it with water. Water goes out through the hole.
Then allow the bottle to fall freely. What do you observe? Why?
Answer:
a) During falling, the entire force of gravity is utilised to give acceleration for the body. So a freely falling body experience weightlessness.

b) While falling, water will not go out through the hole. During free fall, water and the bottle possess some acceleration. Gravitational force of attraction is utilized to give acceleration to the body.

Question 16.
A car is moving with a uniform velocity of lo rn/s. It is brought to rest by applying brake uniformly for 2 s.
a) Is there acceleration or retardation? Calculate.
b) What is the displacement of car during this time interval?
Answer:
a) There is retardation
u = 10 m/s, t = 2 s, v = 0
a = \(\frac{v-u}{t}\)
a = \(\frac{0-10}{2}\) = -5m/s²
Retardation = 5m/s²

b) S = ut + \(\frac{1}{2}\)at²
= 10 × 2 + \(\frac{1}{2}\) ×(-5 × 2²)
= 20 – 10 = 10m

Question 17.
Ray diagram showing the path of light through mediums A and B is given.

a) In which medium will the speed of light be less – A or B?
b) Which will be the optically denser medium? Justify your answer.
Answer:
a) Speed of light will be less in medium B.

b) B is the optically denser medium. Here, when light enters from A to B. the light ray deviates towards the normal It happens when light enters from an optically rarer medium to a denser medium. So B will be the optically denser medium.

Question 18.
A truck of mass 1000 kg moves with a velocity of 12 m/s. Within a small Interval of the time the velocity becomes 10 m/s.
a) What is the initial momentum of the lorry?
b) What is its final momentum?
C) What is the change in momentum?
Answer:
u = 12 m/s, v = 10 m/s, m = 1000 kg
a) Initial momentum
p = mu = 1000 × 12 = 12000 kg m/s

b) Final momentum
p = mv = 1000 × 10 = 10000 kg m/s

c) Change in momentum = mv – mu = 10000 – 12000 = – 2000 kg m/s

Question 19.
Write down instances where the force of gravity is fell.
Answer:

• Mango falling down form a mango tree.
• Stone which is thrown upwards comes back to the ground.
• Raindrops fall downwards.
• When we open the bottle filled with water and keep it upside down, water flows out.
• An object in our hands falls down when it is released.

III. Answer any two questions from 20 to 22. (4 score each) (2 × 4 = 8)

Question 20.
Figure shows the path of the light from a laser torch that passes through water taken in beaker.

a) Explain the phenomenon responsible for the deviation of the path of light.
b) What is meant by optical density?
C) What Is the relation between optical density and velocity of light?
d) Arrange the following media in the descending order of their optical density.
(glass, water, diamond, air)
Answer:
a) Refraction-When a ray of light entering obliquely from one transparent medium, to another, its path undergoes a deviation at
the surface of separation. This is refraction.

b) Ability of a medium to influence the velocity of light is called optical density.

C) Invesely proportional

d) Diamond >Glass>Water>Air

Question 21.
Data about the motion of a bus which move in straight line given in the table

Time	0	5	10	15	20	25
Velocity(m/s)	10	10	10	10	10	10

a) Draw velocity – time graph
b) Calculate the displacement between lOs and 20 5.
c) Velocity of the bus is ______
(uniform) non uniform)
d) What is the acceleration of the bus?
Answer:

b) Displacement between 10 s and 20 s
s = Area of rectangle ABCD
= AB × AD
= 10 × 10 = 100m

c) Uniform

d) Zero
If an object moves in a straight line with uniform velocity, it has no acceleration.

Question 22.
a) Give two examples for impulsive force.
b) Why does the gun recoil while shot is fired?
c) We can not walk along mossy surface. Why?
Answer:
a) Batting the cricket ball
Striking a nail on a wall

b) The gun recoils due to the reaction force applied by the shot to the gun.

C) Absence of reaction force is the cause for this.