Question: A ball thrown vertically upward from a roof 60 m above the ground. The ball rises, then falls to the ground. The initial velocity of the ball is 23.4 m/s.

At t=2.39 s, what is the velocity of the ball?

**Solution:**

Time required to reach the highest point (during the upward motion from the roof) = T_{up} = U/g = 23.4/9.8 = 2.39 sec

So at 2.39 s, the ball will be just at the maximum height point of the vertical motion taken.

And, we know that at the maximum height, the velocity of the ball becomes zero.

Hence, the answer to the question is: zero

**At t=2.39 s, the velocity of the ball is zero.**

At