Science - Force and Laws of Motion
Exam Duration: 45 Mins Total Questions : 30
On which of the following do actionreaction forces act upon?
- (a)
Same body
- (b)
Different bodies
- (c)
Along different lines
- (d)
In the same direction
A force produces an acceleration of 5.0 cm S-2 when it acts on a body of mass 20 g. Find the force acting on the body.
- (a)
1 x 10-3 N
- (b)
2 x 10-3 N
- (c)
4 X 10-3 N
- (d)
5 x 10-3 N
A force eas one body of mass 200. The velocity of the body changes from 15 m S-1 to 25 m S-1 in 2.5 s. What is magnitude of the force, assuming the force to be constant
- (a)
0.4 N
- (b)
0.5 N
- (c)
0.6 N
- (d)
0.8
A body of mass 300 g at rest breaks into two parts due to internal forces. One part of mass 200 g is found to move at a velocity of 12 m S-1 towards east. Find the velocity of the other part.
- (a)
- 24 m S-1 towards west
- (b)
14 m S-1 towards east
- (c)
24 m S -1 towards north
- (d)
54 m S -1 towards south
Due to an impulse, the change in the momentum of a body is 1.8 kg m S-1. If the duration of the impulse is 0.2 s, then what is the force produced in it?
- (a)
9N
- (b)
8N
- (c)
7N
- (d)
6N
On what principle does ajet engine work?
- (a)
Conservation of linear momentum
- (b)
Conservation of kinetic energy
- (c)
Conservation of angular momentum
- (d)
Conservation of inertia
A ball of mass 100 g is moving with a velocity of 10m S-1. The force of the blow by the bat acts for 0.01 seconds. What is the force exerted on the ball by the bat?
- (a)
100 N
- (b)
200 N
- (c)
300 N
- (d)
400 N
A body is at rest on the surface of the earth. Which of the following statements is correct?
- (a)
Only the weight of the body acts on it.
- (b)
Only upward force acts on the body.
- (c)
Frictional force acts on the body.
- (d)
Net upward force is equal to the net downward force
A 60 kg man pushes a 40 kg man with a force of 60 N. With what force does the 40 kg man push the other man?
- (a)
40 N
- (b)
0 N
- (c)
60 N
- (d)
20 N
A cricket ball weighing 100 g and moving with a speed of 20 m s' strikes a bat and remains in contact with it for 0.1s. What is the force exerted by the ball on the bat?
- (a)
100 N
- (b)
-10 N
- (c)
-40 N
- (d)
1 N
If soldiers had the options to use guns of different weights but the bullets used are of a fixed weight, what would they prefer and why?
- (a)
Light guns, because handling them is easy
- (b)
Heavy guns, because they can be held firmly
- (c)
Heavy guns because they have less recoil
- (d)
Light guns, because they can be carried easily
A force acts for 10 s on a body of mass 10 kg after which the force ceases and the body travels 50 m in the next 5 s. Find the magnitude of the force.
- (a)
5 N
- (b)
10 N
- (c)
15 N
- (d)
50 N
If the same force is applied on two bodies of different masses for the same time, what happens to the momentum of the two bodies?
- (a)
The momenta increases
- (b)
The momenta decreases
- (c)
The momenta remains the same
- (d)
The momenta may increase or decrease
Match the entries in Column I with those in Column II.
Column-I | Column-II | ||
a) | Force | 1. | N m-2 |
b) | Weight | 2. | Kg |
c) | Pressure | 3. | N |
d) | Impulse | 4. | N s |
e) | Mass | 5. | kg wt |
- (a)
a-3,b-2,c-4,d-l,e-5
- (b)
a-5,b-4,c-3,d-l,e-2
- (c)
a-5,b-4,c-3,d-l,e-2
- (d)
a-4,b-2,c-l,d-3,e-5
A cricket ball of mass 120 g is moving with a velocity of 12 m s-1. It turns back and moves with a velocity of 20 m s-1 when hit by a bat. Find the impulse if the force acts on the ball for 0.02 s.
- (a)
4 N s
- (b)
8 N s
- (c)
32 N s
- (d)
192 N s
The accelerated motion of a body changes due to change in
- (a)
speed.
- (b)
direction of motion
- (c)
constant velocity
- (d)
Both (A) and (B)
A man weighing 60 kg is walking with a uniform velocity of 4 m s-1. Calculate the momentum of a man.
- (a)
120 m s-1
- (b)
240 m s-1
- (c)
360 m s-1
- (d)
480 m s-1
Two bodies have masses in the ratio of 3 : 4. When the same force is applied on both the bodies, the first body produces an acceleration of 6 m S-2. What is the acceleration produced by the second body?
- (a)
2 m S-2
- (b)
4.5 m S-2
- (c)
12 m S-2
- (d)
18 m S-2
A bullet of mass20 g is fired from a rifle of 8 kg with an initial velocity of 100 m s-1. Find the final velocity of the recoil of the rifle.
- (a)
- 0.25 m s -1
- (b)
2.5 m s-1
- (c)
25 m s-1
- (d)
250 m s-1
A force of 100 N acts on a body of mass 2 kg for 10 s. Find the change in the velocity of the body.
- (a)
100 m s-1
- (b)
250 m s-1
- (c)
500 m s-1
- (d)
1000 m s-1
A force acts on a body of mass 3 kg such that its velocity changes from 4 m S-1 to 10m S-1. Calculate the change in the momentum of the body.
- (a)
2 kg m S-1
- (b)
14 kg m S-1
- (c)
18 kg m S-1
- (d)
42 kg m S -1
Which of the following balls is easier to catch eventhough all of them are moving with the same velocity?
- (a)
Tennis ball
- (b)
Cricket ball
- (c)
Basket ball
- (d)
Both cricket and basket ball
A machine gun of mass 12 kg fires 25 g bullets at the rate of 4 bullets per second with a velocity of 500 m S-1. What force must be applied to the gun to hold it in position?
- (a)
20 N
- (b)
12.5 N
- (c)
50 N
- (d)
75 N
Which of the statements given below are applicable for an object to move in a circle?
- (a)
The object must continuously slow down.
- (b)
The object must accelerate.
- (c)
The object must be acted on by external balanced forces.
- (d)
The object must move with uniform velocity.
A gun fires a bullet of mass 50 g with a velocity of 30 m S-1. Because of this, the gun is pushed back with a velocity of1 m S-1. What is the mass of the gun?
- (a)
3.5 kg
- (b)
30 kg
- (c)
1.5 kg
- (d)
20 kg
What is the average force necessary to stop a hammer with a momentum of 25 N s in 0.05 s?
- (a)
500 N
- (b)
125 N
- (c)
50 N
- (d)
25 N
A scooter of mass 120 kg is moving with a uniform velocity of 108 km h-1. Calculate the force required to stop the vehicle in0.1 s.
- (a)
26000 N
- (b)
36000 N
- (c)
46000 N
- (d)
56000 N
A lift is moving down with a retardation of 5 m S-2. Calculate the percentage change in the weight of the person in the lift (g = 10m S-2).
- (a)
-25
- (b)
-50
- (c)
-75
- (d)
-100
A force of 200 N acts on a body of mass 2 kg for 10 s. Find the change in the momentum of the body.
- (a)
1000 N s
- (b)
250 N s
- (c)
500 N s
- (d)
2000 N s
Physical independence of force is a consequence of 'X' Identify 'X'.
- (a)
Newton's third law of motion
- (b)
Newton's second law of motion
- (c)
Newton's first law of motion
- (d)
All of the above