A tennis ball is dropped on to the floor from a height of $9.8\,m$. It rebounds to a height $5.0\,m$. Ball comes in contact with the floor for $0.2\,s$. The average acceleration during contact is $……….ms ^{-2}$. [Given $g =10\,ms ^{-2}$ ]

A boy standing on a stationary lift (open from above) throws a ball upwards with the maximum inttial speed he can, equal to $49\; m s ^{-1} .$ How much time does the ball take to return to his hands? If the lift starts moving up with a uniform speed of $5\; m s ^{-1}$ and the boy again throws the ball up with the maximum speed he can, how long does the ball take to return to his hands?

A body is thrown vertically upwards and takes $5$ seconds to reach maximum height. The distance travelled by the body will be same in

A ball is projected upwards from a height $h$ above the surface of the earth with velocity $v$. The time at which the ball strikes the ground is

A particle is dropped under gravity from rest from a height $h{\,}(g = 9.8\,m/{\sec ^2})$ and it travels a distance $9h/25$ in the last second, the height $h$ is……… $m$