Kerala Syllabus Class 9 Physics Model Question Paper Set 2 English Medium

Teachers recommend solving Kerala Syllabus 9th Standard Physics Question Paper Set 2 to improve time management during exams.

Kerala Syllabus Std 9 Physics Model Question Paper Set 2 English Medium

Time: 1½ Hours
Max Score: 40 Marks

Instructions:

• First 15 minutes is given as cool off time. This time is to be spent for 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
Give one example for atmospheric refraction.
Answer:
Twinkling of stars

Question 2.
The unit of impulse is ___________
Answer:
Ns

Question 3.
What would be the weight of a body of mass 50kg when placed at the centre of the earth?
Answer:
Zero

Question 4.
The area under a velocity-time graph gives _________
(Velocity. displacement. distance, time)
Answer:
Displacement

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

Question 5.
An object starting from rest travels with an acceleration of 6 m/s².What will be its velocity after 8s?
Answer:
u = 0,
a = 6 m/s², t = 8s
v = u + at
v = 0 + 6 × 8
v = 48 m/s

Question 6.
Is it dangerous for loaded vehicles to negotiate a curve in the road without reducing speed? What is the reason?
Answer:
Yes. This is because loaded vehicles possess more inertia of motion. As mass increases, inertia also increases.

Question 7.
The bottom of a pond appears elevated when viewed from a distance than from a nearer point. Why?
Answer:
When the light coming from the bottom of the pond enters from an optically denser medium to a rarer medium, it deviates away from the normal. As the distance between the pond and the observer increases, the angle of refraction made by the incident ray increases. So the bottom of a pond appears elevated.

Question 8.
If a stone of mass 10 kg and another of mass 5 kg fall down simultaneously from the top of a building. Which one will reach the ground first? Why?
Answer:
Reach at the same time Acceleration due to gravity g = \(\frac{G M}{R^2}\) does not depend on mass of the body.

Question 9.
What are the two conditions required for total internal reflection to occur?
Answer:
The conditions required for total internal reflection to occur are
a) The ray should enter from an optically denser medium to a rarer medium.
b) The angle of incidence should be greater than the critical angle.

Question 10.
Rockets are used to launch artificial satellites.
a) State the law of motion related to the rocket launching.
b) Write down some examples for this law.
Answer:
a) For every action there is an equal and opposite reaction
b) When a man jumps from a boat to the shore, the boat moves backward.
When a bullet is fired from a gun the gun recoils.

Question 11.
A car is moving with a uniform velocity of 20 m/s. It is brought to rest by applying brake uniformly for 5s.
a) What is the retardation of the car?
b) What is the displacement of the car during this time interval?
Answer:
a) u = 20 m/s, t = 5 s, v = 0 m/s
a = (v-u)/t = (0 – 20)/5 = (-20)/5
a = -4 m/s²

b) s = ut + 1/2 at²
s = 20 × 5 + 1/2 × – 4 × 25
s = 100 -50 = 50 m

Question 12.
Explain how optical fibres make use of the property of total internal reflection
Answer:
Light rays from the source travel through the fibre. While travelIng through the fibre, it makes an angle of incidence greater than the critical angle with the walls of the fibre Hence the light undergoes successrve total internal reflection and emerges through the other end.

Question 13.
The force of attraction between two persons was not experienced in everyday life Why?
Answer:
The force of attraction between two persons is not felt because it is very feeble. This force is very small that it cannot even be compared to other forces like frictional force, magnetic force, etc. Therefore, this force is not experienced In everyday life.

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

Question 14.
State if the following statements are right or wrong and correct the wrong statements
a) We can see the apparent position of the Sun just before and just after the actual Sunrise and actual Sunset due to atmospheric refraction.
b) A ray incident normally at the surface of separation of mediums undergoes refraction.
c) As the refractive index inŒeases, the speed of light increases.
Answer:
a) Right

b) wrong
Corrected statement: A ray incident normally at the surface of separation of mediums undergoes no refraction.

C) Wrong
Corrected statement As refractive index increases, speed of light decreases.

Question 15.
Give reasons
a) When a bullet is fired from a gun. the gun recoils.
b) When a bus at rest suddenly moves Forward, the passengers, standing lithe bus fall backwards.
C) We slip on a mossy surface.
Answer:
a) The gun recoils due to the reaction force applied by the shot to the gun. Forward movement of the shot Is action and the backward movement of the gun is reaction.
b) Inertia of rest is the reason. The passengers tends to continue in the state of rest.
c) The absence of reaction force is the cause for this.

Question 16.
The mass and weight of a body is determined at the pole and at the equator
a) Is there any difference in the mass?
b) Is there any change in the weight?
C) Justify the answer.
Answer:
a) No change in mass
b) Yes. Chan9e will occur
C) Mass is the quantity of matter present In a body.
Value of g is greater at the poles and lesser at the equator. So weight varies. Value of g does not affect the mass.

Question 17.
a) Draw the velocity-time graph based on the table.

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

b) Find out the displacement between 10 s and 20 s from the graph.
Answer:
a)
b) Displacement = Area of rectangle = length × breadth = 20 × 10 = 200 m

Question 18.
A loaded lorry of mass 1500 kg moves with a velocity of 12 m/s. Within a small interval of 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 expression for change in momentum?
Answer:
a) Initial momentum p = mv₁, m = 1500 kg
v₁ = 12 m/s
mv₁ = 1500 × 12 = 18000 kgm/s

b) Final momentum p = mv₂
v₂ = 10 m/s
p = 1500 × 10
= 15000 kgm/s

c) Expression for change in momentum = mv₂ – mv₁

Question 19.
The mass of an object is 100 kg. Calculate its weight at the centre of the Earth, the polar region, the equatorial region, the Moon. and the Jupiter (g on the Jupiter 23.1 m/s²)
Answer:
m = 100 kg
At the centre, w = mg = 100 × 0 = 0N
At the poles, w = mg = 100 × 9.83 = 983 N
At the equator, w = mg = 100 × 9.78 = 978 N
On Moon, w = mg = 100 × 1.62 = 162 N
On Jupiter, w = mg = 100 × 23.1 = 2310 N

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

Question 20.
Observe the figure. Light falling on two different media are shown.

a) Which medium has greater optical density? Through which medium will light pass through higher speed?
b) Why?
C) Which medium has greater refractive index?
d) What do you mean by refractive index of a medium?
Answer:
a) Medium 2 has greater optical density Through medium 1 light passes with higher speed.
b) Optical density is greater in the medium having less refracted angle.
c) Medium 2
Because medium 2 possess greater optical density.
d) Refractive index of a medium is the ratio of the speed of light in vacuum to the speed of light in the medium.

Question 21.
Observe the figures.

a) In which figure the attractive force is greater?Why?
b) Calculate the attractive force in figure B.
Answer:
a) A
It is because comparing to figure B , the distance is less in figure A. The attractive force is inversely proportional to distance between the two attracting bodies.

b) m₁ = 5 kg
m₂ = 20 kg
d = 10 m
F = \(G \frac{m_1 m_2}{d^2}\)
F = \(\frac{6.67 \times 10^{-11} \times 5 \times 20}{10^2}\)
F = 6.67 × 10_-11N

Question 22.
Motion of a car is show, below using a diagram.

a) What is the distance covered by the car between A and C?
b) Find the velocity of the car during this period.
c) Among the following which are the time interval where car travels in uniform velocity?
(Os → 2s, 2s→4s, 4s→6s,8s→10s)
Answer:
a) 25 m

b) Velocity = \(\frac{\text { Displacement }}{\text { Time }}\)
Velocity = \(\frac { 25 }{ 4 }\) = 6.25 m/s

c) 0 s → 2s, 4s → 6s, 8 s → 10 s