$A$ balloon is at a height of $81\, m$ and is ascending upwards with a velocity of $12\, m/s$. $A$ body of $2\, kg$ weight is dropped from it. If $g = 10\, m/s^2$,the body will reach the surface of the earth in ......... $s$.

$A$ ball is dropped on the floor from a height of $10 \, m$. It rebounds to a height of $2.5 \, m$. If the ball is in contact with the floor for $0.01 \, s$,the average acceleration during contact is:

With what velocity should a ball be projected vertically so that the distance covered by it in the $5^{th}$ second is twice the distance it covers in its $6^{th}$ second? (Take $g = 10 \, m/s^2$)

Two balls $A$ and $B$ are thrown with the same velocity $u$ from the top of a tower of height $h$. Ball $A$ is thrown vertically upwards and ball $B$ is thrown vertically downwards. If $t_A$ and $t_B$ are the respective times taken by the balls $A$ and $B$ to reach the ground,then identify the correct statement.

$A$ food packet is dropped from a helicopter rising up with a velocity of $4 \, ms^{-1}$. The velocity of the packet after $3 \, s$ will be ....... $ms^{-1}$. (in $.4$)

$A$ balloon starts rising from the ground with an acceleration of $1.25\, m/s^2$. After $8\,s$,a stone is released from the balloon. The stone will $(g = 10\, m/s^2)$: