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What is Physics Good For?

Warming up on... Potential

This assignment is due before 9 AM, Wednesday, September 7^th, 2007.

Please type your last name and first initial (e.g., Rader, A):

Please type a nickname: (in case your answer gets used in class).

The following three questions refer to the material you were to read in preparation to the lesson. Questions one and two require you to write a three or four sentence response. Number three is a multiple choice question. Click in the appropriate circle.

You may change your mind as often as you wish. When you are satisfied with your responses, click the SUBMIT HOMEWORK button at the bottom of this page.

WarmUp questions are worth 4 points each.

1.

Consider the graph above. This could be the graph of gravitational potential energy vs. radius of orbit for a satellite orbiting the Earth.

Could it also be the electric potential energy for a positive charge as a function of radius near another positive charge? How about the potential energy for a negative charge as a function of radius near a positive charge? Could it be the electric potential vs. distance for a positive or a negative charge? Please explain what this could or could not be and why.

2.

Estimate the total charge that passes through a typical lightbulb in one second. You may assume that the voltage across the bulb is 120 V.
Hint: You do know how much energy is typically used by a bulb in one second.

3.

According to section 23-5, the potential difference is the integral of the E field (eq. 23-17), and the E field is the "gradient" of V (eq 23-22). Describe the similarities and differences between this and another pair of fields that are more familiar: wind speed and air pressure.

Hint: It is a litle more complicated in real weather patterns, but, roughly speaking, wind does blow from high pressure areas to low pressure areas.

Below is a space for your thoughts, including general comments about today's assignment. What was hard or confusing (or cool)? What would you like to spend extra time on in class? Do you see how this subject fits in with the others we have discussed?

You may change your mind as often as you wish. When you are satisfied with your responses click the SUBMIT button.

This site is made possible by funding from the National Science Foundation (DUE-9981111).

This assignment is due before 9 AM, Wednesday, September 7th, 2007.

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This assignment is due before 9 AM, Wednesday, September 7^th, 2007.