22.

A 6.8-kg rock and a 8.1 x 104-kg pebble are held near the surface of the earth. (a) Determine the magnitude of the gravitational force exerted on each by the earth. (b) Calculate the magnitude of the acceleration of each object when released. (a) Frock = i Fpebble = i (b) arock = i pebble = iA 63.0-kg crate rests on a level floor at a shipping dock. The coefficients of static and kinetic friction are 0.630 and 0.255, respectively. What horizontal pushing force is required to (a) just start the crate moving and (b) slide the crate across the dock at a constant speed? (a) Number i Units (b) Number i UnitsA car [m = 164C! kg] is parked on a road that rises 11" above the horizontal. What are the magnitudes of {a} the normal force and {hi the static frictional force that the ground exerts on the tires? [3} Number l Units v [b] Number l Units v Consult Multiple-Concept Example 9 to explore a model for solving this problem. A person pushes on a 59-kg refrigerator with a horizontal force of -260 N; the minus sign indicates that the force points in the -x direction. The coefficient of static friction is 0.65. (a) If the refrigerator does not move, what are the magnitude and direction of the static frictional force that the floor exerts on the refrigerator? (b) What is the magnitude of the largest pushing force that can be applied to the refrigerator before it just begins to move? Assumeg = 9.8 m/s?. (a) Static frictional force i (b) Magnitude of largest force =