Imagine that you have a bicycle wheel that you start spinning. Then you place your hand on the wheel to stop it.
1. What kind of energy does the wheel have once it is stopped? *
2. What kind of energy does the wheel have while it is spinning? *

The free body diagram shows a box being pulled to the left up a 25-degree incline. the magnitude of the normal force is

You are driving directly behind a pickup truck, going at the same speed as the truck. a crate falls from the bed of the truck to the road. (a) will your car hit the crate before the crate hits the road if you neither brake nor swerve? (b) during the fall, is the horizontal speed of the crate more than, less than, or the same as that of the truck?

1. jay fills a wagon with sand (about 20 kg) and pulls it with a rope 30 m along the beach. he holds the rope 25° above the horizontal. the rope exerts a 20-n tension force on the wagon. how much work does the rope do on the wagon?