1. A student with mass 42 kg jumps off a high diving board. a) Using 6.010^24 kg for the mass of the earth, what is the acceleration of the earth toward her as she accelerates toward the earth with an acceleration of 9.8 m/s^2 ? Assume that the net force on the earth is the force of gravity she exerts on it. Express your answer in meters per second squared.

2. A chair of mass 13.5 kg is sitting on the horizontal floor; the floor is not frictionless. You push on the chair with a force F = 45.0 N that is directed at an angle of 40.0 below the horizontal and the chair slides along the floor. a) Use Newton's laws to calculate the normal force that the floor exerts on the chair. Express your answer in newtons.

3. A man pushes on a piano with mass 190 kg ; it slides at constant velocity down a ramp that is inclined at 15 above the horizontal floor. Neglect any friction acting on the piano. a) Calculate the magnitude of the force applied by the man if he pushes parallel to the incline. Express your answer with the appropriate units. b) Calculate the magnitude of the force applied by the man if he pushes parallel to the floor. Express your answer with the appropriate units.

4. A rocket of initial mass 105 kg (including all the contents) has an engine that produces a constant vertical force (the thrust) of 1720 N. Inside this rocket, a 19.5 N electric power supply rests on the floor. (Hint: Start with a free-body diagram for the power supply.) a) Find the initial acceleration of the rocket. Express your answer with the appropriate units. b) When the rocket initially accelerates, how hard does the floor push on the power supply? Express your answer with the appropriate units.