Problem 1.173

A particle of mass \(m\) having collided with a stationary particle of mass \(M\) deviated by an angle \(\pi / 2\) whereas the particle \(M\) recoiled at an angle \(\theta=30^{\circ}\) to the direction of the initial motion of the particle \(m .\) How much (in per cent) and in what way has the kinetic energy of this system changed after the collision, if \(M / m=\) \(=5.0 ?\)