$A$ ball is dropped from a bridge $122.5\, m$ above a river. After the ball has been falling for $2\, s$,a second ball is thrown straight down after it. What must its initial velocity be so that both hit the water at the same time?.......$m/s$

$A$ ball is thrown upwards from the top of a tower $40\,m$ high with a velocity of $10\,m/s$. Find the time when it strikes the ground (in seconds). Take $g = 10\,m/s^2$.

$A$ stone is thrown with an initial speed of $4.9 \, m/s$ from a bridge in a vertically upward direction. It falls down into the water after $2 \, s$. The height of the bridge is .......... $m$.

Four marbles are dropped from the top of a tower one after the other with an interval of one second. The first one reaches the ground after $4$ seconds. When the first one reaches the ground,the distances between the first and second,the second and third,and the third and fourth marbles will be respectively:

$A$ 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 $.4$)

Which of the following statements is correct?