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2:Synchronous communications satellites are placed in a circular orbit that is 4.37 x 108 m above the surface of the earth. What is the magnitude of the acceleration due to gravity at this distance?

3:A 4.42-kg box is sliding across the horizontal floor of an elevator. The coefficient of kinetic friction between the box and the floor is 0.392. Determine the kinetic frictional force that acts on the box when the elevator is (a) stationary, (b) accelerating upward with an acceleration whose magnitude is 1.79 m/s2, and (c) accelerating downward with an acceleration whose magnitude is 1.79 m/s2.

4:A crate is resting on a ramp that is inclined at an angle above the horizontal. As is increased, the crate remains in place until reaches a value of 31.1°. Then the crate begins to slide down the slope. (a) Determine the coefficient of static friction between the crate and the ramp surface. (b) The coefficient of kinetic friction between the crate and the ramp is 0.380. Find the acceleration of the moving crate.

5:Traveling at a speed of 10.3 m/s, the driver of an automobile suddenly locks the wheels by slamming on the brakes. The coefficient of kinetic friction between the tires and the road is 0.670. How much time does it take for the car to come to a halt? Ignore the effects of air resistance.