Answer:
The speed of the stone before it hit the river 3.00 sec later. Let v is the velocity at that instant is 45 m/s.
Explanation:
Given that, a child threw a stone straight down off a high bridge.
Initial velocity of the stone, u = 15 m/s
We need to find the speed of the stone before it hit the river 3.00 sec later. Let v is the velocity at that instant. When it come down, it is moving under the action of gravity. Using equation of motion as :

So, the speed of the stone before it hit the river 3.00 sec later. Let v is the velocity at that instant is 45 m/s.
Answer:
The length of the rod should be

Explanation:
Period of simple pendulum is given by

We have

The length of the rod should be
