A 300 g ball swings in a vertical circle at the end of a 1.3-m-long string. When the ball is at the bottom of the circle, the tension in the string is 13 N. What is the speed of the ball at that point?

Consider a small frictionless puck perched at the top of a fixed sphere of radius r. if the puck is given a tiny nudge so that it begins to slide down, through what vertical height will it descend before it leaves the surface of the sphere? [hint: use conservation of energy to find the puck's speed as a func e conservation of energy to find the puck's speed as a function of its height at what value of this normal force does the puck leave the sphere? ] here on the puck.