1) Determine the height above the surface of a planet with radius R and mass M at which the acceleration due to gravity will be one half its surface value.

2) You find a 0.065 kg piece of wood attached to a string and decide to try to whirl is over your head in a horizontal circle. It makes 2.5 revolutions every second in a circle of radius 1.2 m.

a. Will the ball swing at an angle above the horizon, below the horizon, or precisely at 0 degrees with respect to the horizon? Why?

b. Determine the angle that the cord makes with the horizontal.

c. What is the tension in the chord?

3) Two blocks are stacked on top of each other and are each at rest. The top box has a mass of 5 kg and the bottom box has a mass of 10 kg. The coefficient of static friction between the blocks is 0.25 and coefficient of kinetic friction is 0.18. The surface that the bottom box rests on is frictionless. A horizontal force of 50N is then applied to the bottom box.

a. Draw a free body diagram for each box.

b. Do the boxes accelerate together at the same rate? Calculate the rate of acceleration of each box.

c. Is the friction between the blocks static or kinetic, why?

**Subject Physics General Physics**