12/10 Earth Science update and homework due 12/17

Hi folks,

This week we talked a bit more about energy in general. We got into a bit more detail about what energy is by having the students expend their energy by pushing my car. We measured the force of their push and the distance they pushed the car to calculate the amount of Joules they used moving the car.

We also got into the concept of energy efficiency. In other words, the amount of useful work you get out of something compared to the energy you put in. For example, an energy efficient car can go farther from the energy in a gallon of gas than a non-energy efficient car.

To play with this concept a bit, the students created the most energy efficient "vehicles" that they could. These vehicles were given energy by being placed on top of a ramp and then released. The most energy efficient vehicles rolled the farthest and the fastest.

For homework next week:
I would like you to compare your energy output to the energy requirements of household items.

Somewhere on most household items is a label that tells you what Wattage that item uses. Compare that item's Wattage to your own.

Remember, when we pushed the car and then calculated your power (the amount of Joules you used per second)? That was your Wattage. (If you can't remember yours, or if you were absent, use the class average which was about 120W.)

Find out how many times more or less is your Wattage compared to the item? For example, a hair dryer can have a Wattage of 1500W. If your Wattage was 150W than the hairdryer needs 10 times more Watts than you can do. (1500 divided by 150 = 10)

Find at least seven different items (refrigerators, light bulbs, computers, TV's, etc) and compare the Wattage you can produce to the Wattage they need. Please write that up and hand that in next week.

There will be no recording this week since most of the class consisted of activities.