MCQ PRACTICE

Welcome to your Ncert - class 9- science - Chapter 9 – Gravitation 1

A body of mass 10 kg is thrown up with a velocity 98ms −1. Simultaneously another is dropped from a tower. After 2 seconds their momenta are found to be same in magnitude. Then the mass of the freely falling body is

20 kg

4 kg

30 kg

40 kg

None

A small spherical ball of radius r falls freely under gravity through a distance of ℎ before entering a tank of water. If, after entering the water, the velocity of the ball does not change, then ℎ is proportional

$r^{4}$

$r^{2}$

$r^{5}$

$r^{3}$

None

The weight of a person reduces to one-sixth on the Moon than on the Earth What changes will you notice in the mass of a person on the Moon in comparison to the Earth?

The mass of the person reduces to half on the moon

The mass of the person remains unchanged on the moon

The mass of the person reduces to one sixth on the moon like weight

The mass of the person reduces to one fourth on the moon

None

Four marbles are dropped from the top of a tower one after the other with an interval of one second. The first one reaches the ground after 4 seconds. When the first one reaches the ground the distances between the first and second, the second and third and the third and fourth will be respectively

20, 10 and 5 m

35, 25 and 15 m

30, 20 and 10 m

40, 30 and 20 m

None

The maximum height from which a person can safely jump is 2.45 m. What is the maximum allowable landing speed for a parachutist?

5.93 m/s

4.93 m/s

6.93m/s

69.3 m/s

None

Two point masses A and B have masses in the ratio of 1 : 4 .The point masses are at distance 1 m apart. At what distance from point mass B. a point mass m is placed so that at that point the resultant force on it zero ?

2/5 m

1/5 m

1/3 m

2/3 m

None

Why do hot air ballons rise and float mid-air?

None of these

The buoyant force of the hot-air balloon is equal to the surrounding air

The buoyant force of the hot-air balloon is less than the surrounding air

The buoyant force of the hot-air balloon is more than the surrounding air

None

If water falls from a tap, then the volume rate of flow of water at depth of ℎ, $(A_{0})$is the area of cross-section of the mouth and $A_{0}/2$ is the corresponding area at depth ℎ)

$$A_{0}\sqrt{\frac{2}{3}gh}$$

$$A_{0}\sqrt{3gh}$$

$$A_{0}\sqrt{2gh}$$

$$2A_{0}\sqrt{gh}$$

None

A body of mass

m is taken to the bottom of a deep mine. Then

Its mass decreases

Its mass increases

Its weight decreases

Its weight increases

None

10.

The moon's radius is 1/4 times that of the earth and its mass 1/80 times that of the earth. If g represents the acceleration due to gravity on the surface of the earth, then on the surface of the moon its value is :

g/5

g/6

g/8

g/4

None

11.

A body falls from height h=200 m. The ratio of distance travelled in each 2 s, during t=0 to t=6 s of the journey is (g=10m/s 2 ):

1:2:3

1:3:5

1:4:9

1:2:4

None

12.

Which of the following statements should be correct for a rocket fired from the earth towards the moon ?

The value of g remains constant throughout the path of the rocket

The value of g first decreases and as the rocket approaches the Moon the value of g increases but now the direction is towards the Moon.

The value of g keeps increasing as the rocket goes to the Moon

The value of g keeps decreasing as the rocket goes to the Moon

None

13.

Which of the following statements about the gravitational constant is true

It is a force

It does not depend on the nature of the medium in which the bodies are kept.

It has no unit

It has same value in all systems of units

None

14.

If the force of gravity suddenly disappears:-

Neither mass nor weight of all bodies will become zero

The weight of all bodies will become zero

Both mass and weight of all bodies will become zero

The mass of all bodies will become zero

None

15.

A ball is dropped from the top of building. The ball takes 0.5s to fall post the 3m length of window some distance from the top of the building. If the velocity of the ball at the top and at the bottom of the window are

$V _{T} and V_{B}$ respectively, then

$V _{T} + V_{B}=4.9ms^{-1}$

$V _{T} + V_{B}=12ms^{-1}$

$V _{T} × V_{B}=1ms^{-1}$

$V _{T} × V_{B}=12ms^{-1}$

None

16.

Who among the following did first give the experimental value of G?

Capernicus

Brook Taylor

Cavendish

None of these

None

17.

At the surface of a certain planet acceleration due to gravity is one-quarter of that on the earth. If a brass ball is transported to this planet, then which one of the following statements is not correct?

The brass ball has same volume on the other planet as on the earth

The mass of the brass ball on this planet is quarter of its mass as measured on the earth

None of the above

The brass ball has same mass on the other planet as on the earth

None

18.

A person weighs 110.84 N on the moon whose acceleration due to gravity is one-sixth of that earth if the value of g on earth is

9.8 ms −2 calculate, acceleration due to gravity on the earth.

2.63 ms −2

1.63 ms −2

1.89 ms −2

2.89 ms −2

None

19.

Which of the following is an application of Archimedes' principle?

All of these

Used in Lactometers

Used in designing ships and submarines

Used in Hydrometer

None

20.

Which of the following can be used for measuring the weight of an object?

Spring Balance

Odometer

Speedometer

Thermometer

None

Chapter 7 - Motion

Chapter 8-Force and Law of Motion

Chapter 9 - Gravitational

Chapter 10 - Work and Energy

CHAPTER 11 - SOUND

Curriculum

NCERT - Class 9 - Science - PHYSICS

Chapter 7 - Motion

Chapter 8-Force and Law of Motion

Chapter 9 - Gravitational

Chapter 10 - Work and Energy

CHAPTER 11 - SOUND

MCQ PRACTICE – 1