A juggler throws balls vertically upwards with same initial velocity in air. When the first ball reaches its highest position, he throws the next ball. Assuming the juggler throws $n$ balls per second, the maximum height the balls can reach is

An object thrown vertically up from the ground passes the height $5 m$ twice in an interval of $10 s$. time of flight is …….. $s$

If a stone projected from ground, takes $4 \,s$ to reach the topmost point of its trajectory, then time of flight is ………. $s$

Three different objects of masses ${m_1},{m_2}$ and ${m_3}$ are allowed to fall from rest and from the same point $‘O’$ along three different frictionless paths. The speeds of the three objects, on reaching the ground, will be in the ratio of

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 forth will be respectively