Q 1. State the second law of motion.
Q 2. Name the unbalanced force which slows down a moving bicycle when we stop pedalling it.
Q 3. Rajat got three solid blocks of wood, plastic and steel. Each block is of the same size and shape. Which block has the highest inertia? Why?
Q 4. A scooter is moving with a velocity of 25 m/s and it takes 5 s to stop after the brakes are applied. If the mass of the scooter along with the rider is 180 kg, find the change in momentum in this case.
Q 5. How much force must be applied on an object of mass 25 kg to accelerate it to a value of 7 ms-2 ?
Q 6. In the given figure, the card on which a coin rests is flicked with a push.
i. What do you observe in this case and why?
ii. State the law involved in this case
iii. What will be your observation if the above coin is replaced by a heavy five rupee coin? Justify your answer.
Q 7. The velocity- time graph of a ball moving on the surface of a floor is shown in the given figure. Find the force acting on the ball if the mass of the ball is 100 g.
Q 8. Velocity- time graph of a moving particle is shown in the figure. How much force acts on the particle? Give reason.
Q 9. Two forces act on an object as shown below. Will the object move? Give reason for your answer.
40 N
45N
Q 10. What is the momentum of a heavy ball of mass ‘M’ is laying at rest on a table?
Q. no.
Q 11. Name the physical quantity which is measured by the rate of change of momentum. State its SI unit.
Q 12. State the law of conservation of momentum.
Q 13. If F and F’ are balanced forces, then what will be the magnitude of Fa?
25 N
Fa F’ = 70 N
Q 14. Why should we wear safety seat belts in a car?
Q 15. State Newton’s third law of motion and explain it with the help of an example.
Q 16. A straw is attached to the surface of a balloon as shown in the given diagram.
In which direction does the straw move when the thread tied to the balloon’s neck is removed? Why?
Q 17. Two identical bullets are fired - one from a light rifle and the other from a heavy rifle with the same force. Which rifle will cause more injury to the shoulder? Why?
Q 18. A car of mass 1000 kg travelling at 12 m/s dashed into the rear of a bus of mass 2000 kg moving in the same direction at 8 m/s. The car bounced backward after the collision with a speed of 9 m/s. What was the velocity of the bus after the collision?
Q 19. A bullet of mass 25g is fired with a horizontal velocity of 130 m/s from a gun of mass 2 kg. What is the recoil velocity of the gun?
Q 20. A body of mass 2 kg is dropped from a height of 20 m. It accelerates uniformly at the rate of 10 m/s2until it hits the ground. Calculate the initial momentum and the momentum just before it strikes the ground.
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