Help with physics with calculus!!! I'm really stuck on two problems.... #1 An astronaut is rotated in a horizontal centrifuge at a radius of 5.0 m. (a) What is the astronaut's speed if the ventripetal acceleration has a magnitude of 7.0g? (b) How many revolutions per minute are required to produce this acceleration? (c) What is the period of the motion? Help with any of them would be greatly appreciated thanks a lot!