Again consider the track and carts in Figure P7.66 with but this time the carts stick to...

Again consider the track and carts in Figure P7.66 with but this time the carts stick together after the collision. (a) Find the height h from which cart 1 would need to start to make sure that both carts complete the loop without leaving the track. (b) Find the height needed if instead the more massive cart is made to collide with the smaller cart.