Energy Problem Set
If so instructed by your teacher, print out a worksheet page for these problems.

 Background:

 Potential energy is stored energy. The chemical energy in a can of gas, the energy in a compressed spring, and the energy in water behind a dam are all examples of potential energy. Potential energy is also called energy of position. In this case the formula for potential energy is: E_p = m * g * h where E_p stands for potential energy and is measured in joules, m stands for mass and is measured in kilograms, g stands for gravity and equals 9.8 m/s², and h stands for height and is measured in meters.

Kinetic energy is energy of motion. The formula for kinetic energy is: E_k = 1/2 * m * V² where E_k stands for kinetic energy and is measured in joules, m stands for mass and is measured in kilograms, and V stands for velocity and is measured in m/s.

When a glider loses altitude it converts potential energy into kinetic energy. This is an example of the law of conservation of energy. When potential energy is converted into kinetic energy, the velocity of the plane or glider increases. The amount of increase can be calculated by solving for velocity in the kinetic energy equation given above.

Problems:

1. A model glider has a mass of 1 kg. How much potential energy does it have 2 meters off the ground?
   
2. The same model has a velocity of 2.2 m/s. How much kinetic energy does it have?
   
3. If the same model descends 2 meters and all it's potential energy is converted to kinetic energy, what is the glider's change in velocity?
   
4. A full-sized glider has a weight of 4,900 N, while it's pilot has a weight of 825 N. If it is 1,000 meters off the ground, how much potential energy do the plane and pilot have?
   
5. The same glider from Problem 4 has a velocity of 35 m/s. How much kinetic energy does it have?
   
6. The same glider from Problem 4 has a velocity of 35 m/s. The glider descends 900 meters. What is it's new velocity?
   
7. Compare the velocity you calculated in Problem 6 to the speed of sound. Is this answer reasonable? Why or why not