How to find the coefficient of friction without the force of friction or vice versa

Aball is thrown horizontally from a cliff at 8m/s .in what direction is the ball moving 2s later?

Which statement best explains why the overall charge on an atom is zero?

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.