A ball weighing 5 kg is being rotated by means of a cord 2 m long.if its velocity is `6 m s^-1` ,find the force that tends to break the cord.

A train 100 m long is moving with a velocity of 60 kmh^-1 . Find the time it takes to cross the bridge 1 km long.

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. Take g=10 m//s^2.

Certain force acting on a 20 kg mass changes its velocity from 5ms ^-1 to 2ms^-1 . Calculate the work done by the force.

A particle of mass 1 kg is whirled uniformly at the end of a string 2 m long.If the string makes 3 revolutins in 1.2 sec., find the tension in the string.

Two pith-balls each weighing 10^-3 kg are suspended from the same point by mans of silk threads 0.5 m long. On charging the pith-balls equally, they are found to repel each other to a distance of 0.2 m. Calculate the charge on each ball?

A railway train 50 m long passes over a bridge 250 m long with uniform velocity of 10 m s ^(-1) . How long will it take to completely pass over the bridge ?

A bob of mass 0.1 kg hung from the ceiling of a room by a string 2 m long is set into oscillation. The speed of the bob at its mean position is 1 m s^-2 . What is the trajectory of the bob if the string is cut when the bob is:- at its mean position.