## Sample Test on Force and laws of Motion

1. Write the Newton’s first law of motion? 1
2. Explain why some of the leaves may get detached from a tree when w vigorously shake the branch. 1
3. What is the momentum of an object of mass m, moving with a velocity v? 1
4. Why is it advised to tie the luggage kept on the roof of a bus with a rope. 1
5. Why a fielder a pulls his hands gradually with the moving ball while holding a catch. 1
6. What is Inertia? 1
7. Write the effects of forces? 2
8. What is the thrust needed to fire a 350 kg rocket straight up with an acceleration of 8m/s2 2
9. Mathematically prove the law of conservation of momentum?  3
10. A constant force acts on an object of mass 5 kg for a duration of 2 s. It increases the object’s velocity from 3 m s–1 to 7 m s-1. Find the magnitude of the applied force. Now, if the force was applied for a duration of 5 s, what would be the final velocity of the object?   3
11. A stone of 1 kg is thrown with a velocity of 20 m s–1 across the frozen surface of a lake and comes to rest after travelling a distance of 50 m. What is the force of friction between the stone and the ice?       3
12. An automobile vehicle has a mass of 1500 kg. What must be the force between the vehicle and road if the vehicle is to be stopped with a negative acceleration of 1.7 m s–2  ?   3
13. From a rifle of mass 4 kg, a bullet of mass 50 g is fired with an initial velocity of 35 m s–1 . Calculate the initial recoil velocity of the rifle      3

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