Question

A body is projected up with an initial velocity u m/s. It goes up to a height h metres in t seconds time. Then it comes back at the point of projection. Considering negligible air resistance, which of the following statement is true? (a) the acceleration is zero (b) the displacement is zero (c) the average velocity is 2h/t (d) the final velocity is 2u when body reaches

Answer 1

If the body is projected upwards with initial velocity u m/s , goes up to the height h in t seconds and comes back to the point of projection, Its displacement is zero. 
As we know that the displacement is the shortest distance between the initial and the final position of the body. So when a body starts its motion from a particular point and comes back to the same point, the difference between the initial and final positions is zero. So, displacement is zero.