Physics XI Karachi Board True and False - Chapter 7

Chapter 7 - Work, Energy and Power
1. The dot product of force and displacement is called power.

2. Work is the scalar product of force and velocity.

3. When the force and displacement are parallel to each other then the work is maximum.

4. The work done on the body is minimum when the force and displacement are perpendicular to each other.

5. The nature of the work is positive when the force and displacement are in the opposite direction.

6. The cross product of force and moment arm is called torque.

7. The dot product of force and velocity is called power.

8. Power is a vector quantity.

9. One joule is equal to 103 erg.

10. One horse power is equal to 550 ft.lb/s.

11. The expression for absolute potential energy of mass m at the surface of the earth is .

12. Power is defined as the rate of doing work.

13. Energy of a body is a vector quantity.

14. Work energy equation is simply law of conservation of energy.

15. The rate of change of momentum multiplied by displacement is called work.

16. The unit of power is watt-hour.

17. Work done in the gravitational field depends upon the path followed.

18. Work done in the gravitational field along a closed path is equal to zero.

19. Einstein’s mass energy equation relation is E = mc2.

20. The tidal energy is due to the rotation of the earth around sun.


21. The dimension of work are ML2T-2.

22. The dimension of work are ML3T-2.

23. Power is the rate of expenditure of energy.

24. When a body falls down from a table then gravitational potential energy transform into kinetic energy.

25. Transformer does not convert one type of energy into another.

26. The unit of work and energy is the same.

27. The energy of a body due to its motion is called kinetic energy.

28. The energy of body due to its change of position is called potential

29. The ability of a body to perform the work is called its power.

30. The source of geothermal energy is the radioactive decay in the earth’s interior.

31. The absolute potential energy of a body in the gravitational field is directly proportional to the mass of the body.

32. The source of nuclear energy is the process of fission of heavy nucleus.

33. The amount of work done in lifting a body from the surface of the earth to the zero point is called the absolute gravitational potential energy.

34. In physics the unit of energy of elementary particles is electron volt.

35. The range of energy of first atomic bomb is about 1012 joules.