A horizontal bridge is built across a river. A student standing on the bridge throws a small ball vertically upwards with a velocity $4 m s^{- 1}$ .
The ball strikes the water surface after $4 s$ . The height of bridge above water surface is
(Take $g = 10 m s^{- 2}$ ):

Question

A horizontal bridge is built across a river. A student standing on the bridge throws a small ball vertically upwards with a velocity

4 m s^{- 1}

.
The ball strikes the water surface after

4 s

. The height of bridge above water surface is
(Take

g = 10 m s^{- 2}

):

Aicharya · Accepted Answer

The formula to calculate the vertical height travelled by the ball is given by

$H = u t - \frac{1}{2} g t^{2} . . . (1)$

Substitute the values of the known parameters into equation (1) to calculate the required height.

$\begin{array}{rcl} H & = & 4 {ms}^{- 1} \times 4 s - \frac{1}{2} \times 10 {ms}^{- 2} \times {(4 s)}^{2} \\ = & - 64 m \end{array}$

Hence, the required height of the bridge above the surface of the river is $64 m$ .

A horizontal bridge is built across a river. A student standing on the bridge throws a small ball vertically…