A stone is dropped from the window of a stationary bus. It takes 4 seconds to reach the ground. In what time the stone will reach the ground when the bus is moving with (a) constant velcity of `72 km h^(-1)` (b) constant acceleration `4 km h^(-1)`?

Explanation

During vertical downward motion. The distanc ecoverd
`S =ut + 1/2 at^(2)`
When bus is moving with a constant velocity or costant acceleration the initial vertical velocity ` u=0`, downwaed acceleration a=h (acceleration due to gravity) also the vertical distance covered ` S=h` (same for both the cases ) so (t) will he same in both the cases which is equal to ` 4 s` in case (a) and ` 4 s` in case (a) and (b).