Question

Making a heat engine that uses its exhaust heat to do work is restricted according to which principle?

second law of thermodynamics

conservation of matter

first law of thermodynamics

conservation of energy

i think its A

Answer 1

We can obviously eliminate B, it's between the other three.

I'm not a pro at physics so I did some Googling and found this neat website:

http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/heaeng.html

Answer 2

"The engine takes energy from a hot reservoir and uses part of it to do work, but is constrained by the second law of thermodynamics to exhaust part of the energy to a cold reservoir."

Answer 3

\(\color{#0cbb34}{\text{Originally Posted by}}\) @Shadow
"The engine takes energy from a hot reservoir and uses part of it to do work, but is constrained by the second law of thermodynamics to exhaust part of the energy to a cold reservoir."
\(\color{#0cbb34}{\text{End of Quote}}\)
Awesome! so i was right(: thank you for finding that

Answer 4

could you help me with a few more?

Answer 5

Post them and I'll see what I can do.

Answer 6

thank you (: