Physics XI Karachi Board True and False - Chapter 5

Chapter 5 - Torque, Angular Momentum and Equilibrium
1. Torque is a vector product of two appropriate vectors.

2. Angular momentum is a scalar product of two appropriate vectors.

3. The magnitude and direction of angular momentum depends on the choice of origin.

4. A particle moving along a line that passes through the origin has zero angular momentum about the origin.

5. The angular momentum of a body which is under the action of central forces is constant.

6. The direction of angular velocity is taken to be the same as that of angular momentum.

7. The torque due to action reaction for is not zero.

8. Angular acceleration is in the same direction as the angular velocity if the latter is decreasing with time.

9. An electron of an atom possesses only orbital angular momentum.

10. The orbital angular momentum of a body is its angular momentum about an axis passing through the body itself.

11. The centre of mass of a body coincides w, its centre of gravity irrespective of its mass and size.

12. Torque is defined as time rate of change of angular momentum.

13. The vector quantity torque depends on the choice of origin.

14. Every point of a rotating body has the same linear velocity.

15. The right hand rule is applied to find the direction of a vector obtained by the vector product of two vectors.

16. Two forces, which form a couple, are perpendicular to each other.

17. The centre of mass of a system of particles coincides with the centre of gravity only in a uniform gravitational field.

18. The direction of torque is perpendicular to the direction of the applied force.

19. It is possible to calculate the torque acting on rigid body without specifying the origin.

20. Torque is independent of location of origin.


21. In the expression for torque is not equal to the moment arm.

22. If the linear velocity of a particle is constant in time then its angular momentum is constant in time about an arbitrary origin.

23. If a particle moves in a straight line then its angular momentum is zero with respect to an arbitrary origin.

24. If a torque on a particle about an arbitrary origin is zero then its angular momentum about that origin is conserved or constant.

25. A body, which is in equilibrium, is always remains at rest.

26. In static equilibrium, the body always remains at rest.

27. Torque is a scalar quantity.

28. If a body rotates according to the needle of clock due to applied force then torque will be clock wise.

29. In rotational equilibrium, the sum of anti clockwise torque is equal to the sum of clockwise torque.

30. The angular momentum of a particle is conserved if the net torque acting on it is zero.

31. Two equal and anti parallel forces acting at two different points on a body form a couple.

32. The direction of angular momentum of a body can be determined by Fleming left hand rule.

33. Applied torque produces angular acceleration.

34. In circular motion, position vectorand linear momentumare perpendicular to each other.

35. The centre of gravity of a uniform circular plate lies at its centre.