10/1 Chemistry update and homework due 10/8

Hi folks,

Today we did a quick overall look at the concept of energy.  We will be dealing with the concept of energy a lot throughout this class and today's lecture was meant to give an nice overall background regarding what energy is and what it does.

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. One Newton is equal to 4 lbs so multiply the weight by 4.)  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))?  The formula for work is W=FD.

2.  Why doesn't down count in the above problem?

3.  If it takes about 40 Newtons 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?

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?