A 70 kg physicsstudentis running down the hall when he bumps into a chair with mass of 30 kg (the chair is not moving). After the collision, the two objects (student and chair) move together with velocity 3m/s.

Sorry i don’t know what to do

An atom's smaller negative particles are at a distance from the central positive particles, so the negative particles are easier to move. 

The answer is  the potential energy of the bob at position b is 1.47 joules.if the maximum height of the bob is 0.45 meters when it swings back,1.323   joules of energy was transformed to thermal energy.hope this