heh! this is my first post!! ok... ive been trying to do this for ages, i think im just doing it the wrong way... its holiday homework so i couldnt ask my teacher i drew a diagram but i think i did it wrong... im just not getting the right answer! ok here it is part of a roller coster track is in the shape of a vertical circle of radius 300m. what is the slowest speed the roller coster can have at the top of the loop so that all the centripetal force is supplied by the roller coaster's weight? :yuck: answer:5.86 m/s could someone please explain how to do this!! stank you!