Two weights, of 9.0 kg and 3.0 kg, are at rest side by side (Figure 4). You apply a force of 30.0 N on the first weight for 5.0 s, and they both slide across the
floor. The larger weight has a force of friction of 18 N, and the smaller weight has a force of friction of
6.0 N.
(a) Calculate the acceleration of the weights during the first 5.0 s.

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.