21.The distance through which a body falls in the nth second is h. The distance through which it falls in the next second is

22.A stone is dropped from a certain height which can reach the ground in 5 second . If the stone is stopped after 3 second of its fall and then allowed to fall again. Then the time taken by the stone to reach the ground for the remaining distance is

23.A body starts from rest and travels is distance x with uniform acceleration, then it travels a distance 2x with uniform speed , finally it travels a distance3x with uniform retardation and comes to rest. If the complete motion of the particle is along a straight line, then the ratio of its average velocity to maximum velocity is

24.A boy takes 90 second to walk up a stalled escalater. However if the escalator is moving and the boy stands on the escalator, he is carried up in one minute. How much time the boy would take to walk up the moving escalator ?

25.A body released from a great height falls freely towards the earth. Another body is released from the same height exactly one second later. The separation between the two bodies two second after the release of the second body is