A car of mass m moving at a speed v1 collides and couples with the back of a truck of mass 3m moving initially in the same direction as the car at a lower speed v2. (Use any variable or symbol stated above as necessary.)
(a) What is the speed vf of the two vehicles immediately after the collision?
vf =
(b) What is the change in kinetic energy of the car-truck system in the collision?
?K =