(b)8.19.Set Up:Use coordinates where is to the right and is upward.Solve:Collision:There is no external horizontal force during the collision so This givesand Motion after the collision:Only gravity does work and the initial kinetic energy of the combined chunks is convertedentirely to gravitational potential energy when the chunk reaches its maximum height habove the valley floor. Con-servation of energy givesand Reflect:After the collision the energy of the system is when it is allkinetic energy and it is when it is all gravitational potential energy.Mechanical energy is conserved during the motion after the collision. But before the collision the total energy of thesystem is 50% of the mechanical energy is dissipated during the inelastic collisionof the two chunks.8.20.Set Up:The collision occurs over a short time interval and the block moves very little during the collision, sothe spring force during the collision can be neglected. Use coordinates where is to the right.
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