1. List two essential conditions for work to be done.
2. What is the SI unit of work done and power?
3. Find the energy in KWh consumed in 10 hours by a machine of power 500 Watt.
4. Is it possible that some force is acting on a body but still the work done is zero?
5. Derive the expression for potential energy.
6. What is the work done by the force of gravity in the following cases ?
(A) satellite moving around the earth in a circular orbit of radius 3000 km.
(B) stone of mass 250 gram is thrown up through a height of 2.5 m.
7. A person holds a bundle of books over his head for 30 minutes, and get tired . Has he done some work or not? justify your answer.
8. Is it possible that a body be in accelerated motion under the action of a force , yet no work is being done by the force ? Explain with an example.
9. Define one watt power.
10. The kinetic energy of an object of mass m moving with a velocity of 5 m/s is 25 Joule . what will be its kinetic energy when it's velocity is doubled and what will be the mass of this body?
Solution:
A. Pdf solution.
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