Need help with showing work for these questions:

7. A spring-loaded toy gun is used to launch a 10 g plastic ball. The spring, which has a spring constant of 10 Nim, is compressed by 10 cm as the ball is pushed into the barrel. When the trigger is pulled, the spring is released and shoots the ball back out horizontally. What is the ball's speed as it leaves the barrel? Assume that friction is negligible.

8. I A boy flies a kite with the string at a 30angle to the horizontal. The tension in the string is 4.5 N. How much work does the string do on the boy if the boy

A. Stands still?

B. Walks a horizontal distance of 11 m away from the kite?

C. Walks a horizontal distance of 11 m toward the kite?

9. If you mix food in a blender, the electric motor does work on the system, which consists of the food inside the container. This work can noticeably warm up the food. Suppose the blender motor runs at a power of 250 W for 40 s. During this time, 2000 J of heat flow from the nowwarmer food to its cooler surroundings. By how much does the thermal energy of the food increase?

10. Iceland has both high geothermal activity, with high temperatures near the surface, and abundant cold surface water. Iceland has many power plants that take advantage of the proximity of these natural hot and cold reservoirs. One plant uses an underground source at 122 C as the hot reservoir and a nearby lake at 5 C as the cold res