Problem $8$: $(14$ points$)$

A glider of mass M travels with a speed v on a frictionless air track and collides with a second glider, whose

mass is $3$M$,$ that is initially at rest. Velcro on the gliders cause them to stick to each other and move as one

after the collision. Show all your work for full credit.

A$)$ what is the final speed of the gliders after the collision?

B$)$ what is the ratio of the final kinetic energy to the initial kinetic energy?