Physics Test 2 Review

Three masses, 1.0 kg, 2.0 kg, and 3.0 kg, are located at (0.0 m, 0.0 m), (1.0 m, 1.0 m), and (2.0 m, -2.0 m), respectively. What is the location of the center of mass (or center of gravity) of this system?

(1.3 m, -0.67 m)

Identify the number of the action/reaction pairs of forces between the car and the road surface when its skidding to stop.

2 pairs (find the number of the action/reaction pairs of forces between two objects by correctly identifying the forces one object affects the other by and applying Newton's third law.)

A particular motor can provide a maximum torque of 110 N • m. Assuming that all of this torque is used to accelerate a solid, uniform, cylindrical flywheel of mass 10.0 kg and radius 3.00 m, how long will it take for the flywheel to accelerate from rest to 8.13 rad/s?

3.33 seconds

A 95-N force exerted at the end of a 0.32-m long torque wrench produces a torque of 15 N • m. What is the angle (less than 90°) between the wrench handle and the direction of the applied force?

30 degrees

A beach ball is thrown straight up, and some time later it lands on the sand. Is the magnitude of the net force on the ball greatest when it is going up or when it is on the way down? Or is it the same in both cases? Explain. Air resistance should not be neglected for a large, light object.

The only contact force is the force of air drag on the ball. The only long-range force is the weight of the ball. Drag always points in the direction opposite to the motion. Thus the weight of the ball and the drag force always reinforce each other if the ball is moving straight up. The net force is larger on the way up.

Describe free body diagrams

and draw them