2. A roller coaster cart of mass m starts is released from rest at point A, slides down the track and around the loop (Radius R=15.0 m). When the cart is at point B, which is at a height R above the ground, its speed is 30.0 m/s. If there is no friction or air resistance present, what must be the initial height h? A,

2. A roller coaster cart of mass m starts is released from rest at point A, slides down the track and around the loop (Radius R=15.0 m). When the cart is at point B, which is at a height R above the ground, its speed is 30.0 m/s. If there is no friction or air resistance present, what must be the initial height h? A,