**DPP – 9S81**

**DPP – 9S81**

**FIRST LAW OF MOTION, INERTIA & SECOND LAW OF MOTION**

**FIRST LAW OF MOTION, INERTIA & SECOND LAW OF MOTION**

1. State the law of Inertia, Explain the type of Inertia.

2. 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. Which would require a greater force –

accelerating a 2 kg mass at 5 m s^{–2} or a 4 kg mass at 2 m s^{-2} ?

4. A motorcar is moving with a velocity of 108 km/h and it takes 4 s to stop after the brakes are applied. Calculate the force exerted by the brakes on the motorcar if its mass along with the passengers is 1000 kg.

5. The velocity-time graph of a ball of mass 20 g moving along a straight line on a long table is given in figure given below.

6. How much force does the table exert on the ball to bring it to rest?

7. A force of 5 N gives a mass m_{1} , an acceleration of 10 m s^{–2} and a mass m_{2} , an acceleration of 20 m s^{-2} . What acceleration would it give if both the masses were tied together?

8. When a carpet is beaten with a stick, dust comes out of it, Explain.

9. Why do you fall in the forward direction when a moving bus brakes to a stop and fall backwards when it accelerates from rest?

10.Explain why some of the leaves may get detached from a tree if we vigorously shake its branch.81