5. What force are people using when they put sand or gravel on icy roads in the winter?

6. What type of friction must you overcome when you

ice skate?

7. What force keeps a roller-coaster car on the track?

8. When you wear a seat belt, you are being protected

from possible harm by what force?

9. What has greater inertia, a large car or a small car

moving at the same speed? Why?

10. If someone is playing in a baseball game, what

are three forces or laws of motion that could affect the game?

chemical energy --> gravitational potential energy --> kinetic energy --> elastic potential energy --> gravitational potential energy

explanation:

when emma starts the hike, the chemical energy stored in her body is used to climb up the mountain, and so she gains gravitational potential energy (because at the end, she will be at a higher height h above the ground). then she goes bungee jumping: as she falls, this gravitational potential energy is converted into kinetic energy (because her speed increases as she falls down), until the point when the rope stretches, and she stops moving. at that moment, all the kinetic energy is converted into elastic potential energy due to the stretching of the rope. then, this energy is released because the rope returns to its natural length, and emma gains a small increase in altitude , so she gains some gravitational potential energy.