Consider a particle which is constrained to move along the surface of the sphere of radius 5, centered at the origin (a) if we write r(t) for the motion, write down the condition 'constrained to move along the surface of the sphere of radius 5 centered at the origin' in terms of r(t) b) explain why, for such a motion, we must have r'(t) r(t) (hint. differentiate c) what can you say about the acceleration? (hint. differentiate your answer from hint. for later use, try to get rid of square roots.) your answer from the previous part the previous part. draw a picture.)