A stone dropped from the window of a stationary railway carriage takes 2 seconds to reach the ground. In what time the stone will reach the ground when the carriage is moving with (a) constant velocity of 80 km. (b) constant acceleration of 2 m?

[prasanna]

The time taken by the freely falling stone to reach the ground is given by

In both the cases, the stone will all through the same height as it is falling when the railway carriage is stationary. Hence, the stone will reach the ground after 2 seconds.