Quiz 10:

1. An object of mass 20.444 kg is located at the top of a 16 m tall building. Calculate the gravitational potential energy of the object with respect to a point 3 m below the top of the building .

2. A bullet of mass 0.0257 kg is fired from a 6 m tall building horizontally with a speed of 1400 m ⁄ s. Calculate its mechanical energy just after it is fired.

3. An object of mass 10 kg is sliding down a friction less inclined plane of length 2 m that makes an angle of 30 deg with the horizontal. Calculate the work done by gravitational force as the object slides from the top of the inclined plane to the ground.

4. An object of mass 2 kg is sliding down a friction less inclined plane of length 6 m that makes an angle of 40 deg. Calculate its speed just before it hits the ground.

5. A roller coaster extends to the ground from a height of 30 m (point A) and then rises to a height of 16 m (point B). An object of mass 14 kg starts at point A with a speed of 7 m ⁄ s. Assuming the roller coaster is friction less, calculate the speed of the object by the time it reaches point B.

6. A certain spring extends by 0.4 m when an object of mass 0.6 kg hangs from it. Calculate the Hook's constant of the spring.

7. Calculate the elastic potential stored by a spring of Hook's constant 350 N ⁄ m when it is compressed by 0.025 m.

8. An object of mass 2.25 kg is brought in contact with a spring of Hook's constant 280 N ⁄ m that is compressed by 0.1 m. If the spring is let go free to expand, calculate the speed by which the object will leave the spring at its relaxed position.

9. Which of the following is not a correct statement.

10. Intially an object has a potential energy of 90 J and a kinetic energy of 200 J. Under the influence of conservative and non-conservative forces its potential energy changed to 45 J and its kinetic energy changed to 40 J. Calculate the work doneby the non-conservative forces.

11. An object of mass 0.05 kg released from a height of 14.5 m has a speed of 2 m ⁄ s just before it hits the ground. Calculate the work done by air resistance.