21.A body weighs 8 g when placed in one pan and 18 g when placed on the other pan of a false balance. If the beam is horizontal when both the pans are empty, the true weight of the body is:

22.A block rests on a rough inclined plane making an angle of 30 degree with the horizontal. The coefficient of static friction between he block and the plane is 0.8. If the frictional force on the block is 10N, the mass of the block in (kg) is: (Take g = 10 m/second square)

23.Two bodies have same mass and speed, then:

24.The ratio of the weight of a man in a stationary lift and when it is moving downwards with uniform acceleration a is 3:2 then the value of a is:

25.A block of mass M is suspended by a string A from the ceiling and another string B is connected to the bottom of the block. If B is pulled on steadily: