PV Gap

Mitchell Said:

Copyright question! Please help!?

We Answered:

If you click on the links for each book on that site, it brings you to the Amazon page, which lists the year of publication, author, publisher, which is pretty much all you need for copyright info as a reference.

Bradley Said:

There are 250 million private vehicles in the US. Can we really use wind or solar energy?

We Answered:

Tell you what.

I'll jump on your drilling bandwagon IF you'll support:

1) Auto manufacturers building or importing vehicles into America are mandated to produce only vehicles capable of getting 50+ mpg within 10 years. (Emergency vehicles excepted)

2) There are no deadline extensions to #1.

3) Failure to meet #1 results in a ban on that manufacturer selling vehicles in America.

4) Safety cannot be compromised to achieve #1.

5) Emission standards must meet or exceed present standards.

6) A tax bonus to manufacturers who can meet this goal in less than 7 years.

The technology IS there.

Rachel Said:

Physics: What is the equilibrium temperature of a collector plate directly facing the sun?

We Answered:

It doesn't matter how big the plate is, but for the sake of making computations easy, let's assume it is 1 m^2 in area. Then the power of the sun hitting it is 650 watts.

As the plate is neither heating nor cooling, the power that the plate is radiating must be equal to 650 watts.

If you don't remember the Stefan-Boltzmann law, you can look it up here http://en.wikipedia.org/wiki/Stefan%E2%8… . From that, P = s * T^4, where P is power, s is the S-B constant, and T is absolute temperature. Set the left side to 650, and you can solve for temperature. Then convert it to Celsius for a more useful answer.

I have ignored the temperature of the air on the assumption that when a solar radiation figure is given, it includes all sources, including the air and blank sky. And also, the problem states (unrealistically) that there is no heat loss by conduction or convection.