Today we did our second part of the "Basics of Energy" lecture were we talked a bit more about what energy is and how to measure it. We talked about Joules, calories and kilocalories. We tried to get a feel for the units by doing the physical labor of deep knee bends and pushing my car.
Homework for this week:
Read the content on this website up to the section on Power.
Answer the following questions.
1. How many Joules would it take to walk up a 2 meter (about 6 feet) flight of stairs if you weigh 100 lbs? (Remember to convert to Newtons.) How many calories would that be? How many times would you have to walk up (remember down doesn't count) that flight of stairs to burn off the Calories from a Snickers bar (250 Calories (remember that's 250,000 calories))?
2. Why doesn't down count in the above problem?
3. If it takes about 10 lbs of force to push a lawn mower and you push it 400 meters to cover the entire lawn, how much work do you do? In Joules? In calories? (Remember to convert to Newtons.)
4. A gallon of gas has 1.3x10^8 J of energy. (that carrot means that the 8 is an exponent. So the number is 1.3 x 10 to the 8th.) How far can a car go if it takes 400 N of force to keep it going?
5. What is potential energy? Give 3 examples.
6. What is kinetic energy? Give 3 examples.
7. If it takes 10,000 J of energy to push a refrigerator 4 m (12 ish ft.) across a kitchen what force does it take to push that fridge?
8. Look up 3 of your favorite activities and tell me how many Calories it takes to do them? How many Joules would that be?
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