Physical Science

1. What is the difference between energy and power? What is a unit of power? How does speed relate to power?

Energy is the ability to do work, while power is a measure of the amount of work done and the time it takes to do the work. A unit of power is a watt. The more quickly a task is completed the more power is used.

2. Explain how a sound is actually a form of energy? In what medium do sound waves travel?

Sound is a form of energy because when a sound wave is created molecules are set in motion and the energy of the sound wave is associated with the kinetic energy of the molecules. Sound is measured in kinetic energy, which is a joule.

3. Give an example of change of energy from potential to kinetic; from kinetic to potential.

A balancing rock has potential energy, but once it falls, it would have kinetic energy. A pendulum is an example of both ways. As it swings up, the kinetic energy is being turned into potential energy, and as it swings down the opposite is happening.

4. What is a trophic level? Give some examples. How much energy is lost at each trophic level?

A trophic level is all organisms tha t get their energy from the same source. About 10% of energy is lost at each trophic level.

5. If you eat 600 calories per day (roughly one dessert) below your energy needs, how long would it take to lose 10 pounds? How long would you have to walk (assuming 80 calories burned per mile walked) to lose 10 pounds?

It would take approximately 58 days to lose 10 pounds. You would have to walk 437.5 miles at 80 calories per mile to lose 10 pounds.

6. What makes a good conductor of heat? What makes a good insulator?

A good conductor of heat is metal. It moves heat rapidly from one molecule to the other. Wood is a good insulator. It impedes the flow of heat.

7. Explain why heat only flows spontaneously from a hot to cold object.

The second law of thermodynamics states that heat will not flow spontaneously from a cold to a hot body....