Question

A) A gram of TNT has about 2700 Joules/gram of chemical potential energy which can be released. A chocolate chip cookie has about 21,000 joules/gram of chemical potential energy. Discuss why we use TNT in mining operations and not chocolate chip cookies.

B) A single square meter of area at the Earth’s surface gets about 1 kilowatt of power from solar energy. ( About 400 Watts can be harvested using electric solar cells.) Given that currently the average power usage by people in the USA is about 2kW per person, and there are approximately 39 million people in California, how much area would be needed to be covered with solar cells to provide all the people in California with power? How does this compare to the total surface area of California?

Answer 1

A) Even though the chocolate chip cookies have more energy per gram than TNT, the enegy is released very slowly. On the other hand, the energy in TNT is released and transformed into heat energy very quickly. This quick release of heat energy makes TNT expand so rapidly that it causes explosion which is not possible for a chocolate cookie.

B) A single square meter of earth's surface gives 400 W of power through solar cells.

The total power usage in California is 2000 x 39 million = 7.8 x 10¹⁰ W

The area required  to be covered with solar cells to provide all the people in California with power is

which is 195 million square meters

The area of California according to google is 420,000 million square meter.

Thus the area required

to be covered with solar cells to provide all the people in California with power is

times the area of California which is a tiny fraction