A ball is projected vertically upward with an initial velocity of $50 \; ms ^{-1}$ at $t =0 \; s$. At $t =2 \,s$. another ball is projected vertically upward with same velocity. At $t= \; \dots \; s$, second ball will meet the first ball $\left( g =10 \; ms ^{-2}\right)$.

A ball falls vertically downward and bounces off a horizontal floor.The speed of the ball just before reaching the floor $\left(u_1\right)$ is equal to the speed just after leaving contact with the floor $\left(u_2\right), u_1=u_2$. The corresponding magnitudes of accelerations are denoted respectively by $a_1$ and $a_2$. The air resistance during motion is proportional to speed and is not negligible. If $g$ is acceleration due to gravity, then

Two balls $A$ and $B$ are placed at the top of $180 \,m$ tall tower. Ball $A$ is released from the top at $t =0 \,s$. Ball $B$ is thrown vertically down with an initial velocity $u$' at $t=2\, s$. After a certain time, both balls meet $100 \,m$ above the ground. Find the value of $u$ in …………… $ms ^{-1}$. [use $g =10 \,ms ^{-2}$ ]

A body is projected up with a speed $'u'$ and the time taken by it is $T$ to reach the maximum height $H$. Pick out the correct statement

A body is thrown vertically upwards. If air resistance is to be taken into account, then the time during which the body rises is