When a particle is thrown vertically upwards,its velocity at one third of its maximum height is $10 \sqrt{2} \, m/s$. The maximum height attained by it is .......... $m$.

An iron block is dropped into a deep well. The sound of the splash is heard after $4.23 \, s$. If the depth of the well is $78.4 \, m$,find the speed of sound in air in $m/s$ $\left(g = 9.8 \, m/s^2\right)$.

$A$ stone is dropped from a height $h$. It hits the ground with a certain momentum $P$. If the same stone is dropped from a height $100\%$ more than the previous height,the momentum when it hits the ground will change by ........... $\%$.

$A$ boy standing on a stationary lift (open from above) throws a ball upwards with the maximum initial 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?

The effective acceleration of a body,when thrown upwards with acceleration $a$,will be:

$A$ ball of mass $m_1$ and another ball of mass $m_2$ are dropped from equal height. If the time taken by the balls are $t_1$ and $t_2$ respectively,then: