A stack of books rests on a level frictionless surface. A force F acts on the stack, and it accelerates at 3.0 m/s². A 1.0 kg book is then added to the stack. The same force is applied, and now the stack accelerates at 2.0 m/s². What was the mass of the original stack?

Which of the following statements is correct according to Newton's first law of motion?

A person of weight 480 N stands on a scale in an elevator. What will the scale be reading when the elevator is accelerating downward at 4.00 m/s²?

An object slides on a level surface in the +x direction. It slows and comes to a stop with a constant acceleration of -2.45 m/s². What is the coefficient of kinetic friction between the object and the floor?