Sahay Sir > Question Answers > Uncategorised (JEE Advanced Physics by BM Sharma + GMP Solutions) > A steel ball weighting 1 kg is fastened to a cord 1 m long and is released when the cord is horizontal . At the bottom of its path the ball strikes a 5-kg steel block initially at rest on a frictionless surface . The collision is elastic . Find the speed of the ball and speed of the block just after collision . (g = 9.8ms−2) [Hint : Apply principal of conservation of momentum and conservation of kinetic energy as the collision is elastic .]

A steel ball weighting 1 kg is fastened to a cord 1 m long and is released when the cord is horizontal . At the bottom of its path the ball strikes a 5-kg steel block initially at rest on a frictionless surface . The collision is elastic . Find the speed of the ball and speed of the block just after collision . (g = 9.8ms−2) [Hint : Apply principal of conservation of momentum and conservation of kinetic energy as the collision is elastic .]

An electron of mass m is involved in head-on collision with an atom of mass M initially at rest . As a result of the collision a certain amount of energy E is stored internally in the atom . What is the minimum initial velocity that the electron must have ?