A stone is projected vertically upwards with velocity 40m/show that the stone will reach the point of projection with the same velocity

Answer 1

net displacement is zero, so there is no change in potential+kinetic energy.

PE = mgh, which has not changed, so KE also has not changed.

Hence, since mass has not changed, and mv^2 has not changed, neither has v^2.

However, v has changed from upward to downward. So, the question is poorly worded. The speed is the same, but the velocity has changed to the opposite direction.