Question

A particle is projected vertically upwards with a velocity u from a point O. When it returns to the point of projection :
(A)its average velocity is zero
(B)its displacement is zero
(C)its average speed is u/2
(D) its average speed is u

Answer 1

(B)its displacement is zero

Answer 2

Since there is no change in position displacement is 0.

So average velocity is also 0.

The distance covered by particle is twice the height covered.

Here, v = 0, u = u m/s and a = 10 m/s^2 (let g= 10 m/s^2)

v²-u² = 2as

s = -u²/2a

Distance covered = | -u²/a | = u²/a (Distance cannot be -ve )

v = u + at, t = -u/a

Average speed = Total distance / Total time = -u