A stone released into the rriver from a bridge .it takes
4s for the stone to touch
the river's water surface
Complete the height of
the bridge from the water
Level​

h = 78.4  m

Explanation:

Given that,

A stone takes 4s for the stone to touch  the river's water surface.

We need to find the height of  the bridge from the water  level​.

Let the height be h. We can use the second equation of motion to find h. So,

So, the height of the bridge from the water level is 78.4  m.

f is prop to m1xm2 double m1 double force