3, Electromagnetic Catapults (60 pts total): Some rollercoasters start out along a flat track, and get accelerated using an electromagnetic catapult. Suppose a roller coaster is supposed to shoot the cars into a circular loop of radius R. What is the minimum speed vi with which the catapult must launch the cars in order for the roller coaster cars to make it all the way around the loop? Assume the coaster rolls without friction