Force and Laws of Motion -IX-Vasu Classes


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Force and Laws of Motion -IX-Vasu Classes

1. Physical quantity which is equal to rate of change of momentum

a) impulse
b) force
c) energy
d) velocity

2. An athelete runs some distance before taking a long jump

a) to warm up his body
b) he loves running
c) his potential energy increases
d) the run before jump helps him take a longer jump due to inertia of motion

3. Weight of a body due to the earth acts

a) vertically upwards
b) vertically downwards
c) horizontal
d) in any direction

4. A ball is dropeed from a height of 10 m and embedded in sand 1m and stops

a) only momentum remains coserved
b) only kinetic energy remains conserved
c) both Momentum and KE are conserved
d) None of the above

5. A constant force of 100N is applied to a body of mass 60 kg moving initially at a speed of 5m/s. What is the change in momentum before it comes to a halt?

a) 300kgm
b) 300Kg-s
c) 300kgm/s
d) None

6. A body of mass 5kg moving with 1m/s collides with another body of mass 2.5kg and moving with a velocity of v in opposite direction. After collision both the bodies comes to rest instantaneously. The value of v is

a) 1m/s
b) 2m/s
c) 0.5m/s
d) None of the above

7. The passanger feels jerk forward when a moving bus stops suddenly. This happens due to

a) Inertia of passanger
b) Inertia of bus
c) gravitational pull of the earth
d) None

8. Newton second law gives measure of

a) acceleration
b) momentum
c) displacement
d) Force

9. Swimming can be explained by

a) Newton's law of gravitation
b) First law of motion
c) second law of motion
d) Third law of motion

10. A car of mass 1000kg is moving at a speed of 36km/hr and collides with a tree and comes to rest in 5seconds. What will be the force exerted by the car on the tree

a) 8000N
b) 400N
c) 3600N
d) 2000N

11. An empty rail car of mass 100kg is at rest on the railway track. A boy of mass 40kg running at 5m/s jumps on the rail car. What is the common speed of the car and boy is

a) 1.4m/s
b) 2.0m/s2
c) 2.0m/s
d) 1.8m/s

12. A bullet of mass 10gm is fired from a rifle. The bullet takes 0.003sec to move through its barrel and leaves it at the speed of 300m/s. What is the force exerted by the gum on the bullet?

a) 4500N
b) 6000N
c) 1000N
d) 1500N

13. When the external force acting on a system is zero , the total linear momentum

a) also zero
b) remains constant
c) remains variable
d) becomes double

14. Any pair of equal and opposite forces is called action-reaction

a) when they act on a single body
b) when they involve two bodies
c) when they cancel out effect of each other
d) None

15. A body moves with a constant velocity of 20m/s for 5 seconds. The mass of the body is 2kg. The force acting on the body is

a) 40N
b) 20N
c) 8N
d) Zero

16. What force would be required to stop a car of mass 1000kg and a loaded truck of mass 10000kg in 2 seconds if they were moving with same velocity of 5m/s

a) -250N ,2500N
b) -2500N ,-250N
c) -250N ,-2500N
d) 250N ,-2500N

17. What is the unit of linear momentum

a) kgm/s
b) kgm/s2
c) m/s2
d) N

18. You have a rubber ball and a stone of same size which one is true

a) both have equal inertia
b) stone has more inertia
c) rubber ball has more inertia
d) None of the above

19. Balanced forces acting on a body

a) can make a body move
b) can bring a moving body to rest
c) can accelerate the body
d) may change the shape of the body

20. If a number of forces acting on a body produce zero acceleration the forces are

a) Balanced
b) Unbalanced
c) Equal acting in same direction
d) None

21. When a cricket player stops a ball gradually

a) he dcreases the velocity of the ball
b) decreases acceleration of the ball
c) Both A and B
d) decreases rate of change of momentum of the ball

22. The working principle of a jet plane is based upon

a) Newton' s First law of motion
b) Second Law of motion
c) Conservation of momentum
d) Newton's third law of motion

23. A cricket player stops a ball by lowering hands

a) this reduces rate of change of momemtum of the ball and hence force applied
b) to grab it tightly
c) to give more runs
d) None

24. A truck and a scooter both are moving at same speed and stops simultaneously which onw will have higher rate of change of momentum

a) Truck
b) Scooter
c) Both will have same rate of change of momentum

25. When a ball is thrown upward it has

a) uniform acceleration
b) uniform retardation
c) non uniform retardation
d) uniform velocity

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