1. What is the maximum possible efficiency for a heat engine operating between heat reservoirs whose temperatures are 800 degrees C and 200 degrees C?
2. An ideal gas is compressed isothermally from 20L to 10L. During this process, 5J of work is done to compress the gas. /what is the change of internal energy for this gas?
I've tried each of them many times and cannot get the right answer (I keep getting 75% for 1 and 5J for 2. My friends don't know how to do this either! Thanks in advance.
2. An ideal gas is compressed isothermally from 20L to 10L. During this process, 5J of work is done to compress the gas. /what is the change of internal energy for this gas?
I've tried each of them many times and cannot get the right answer (I keep getting 75% for 1 and 5J for 2. My friends don't know how to do this either! Thanks in advance.
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1. Convert degrees C to Kelvin before calculating efficiency and you'll get it right.
2. Change in internal energy is 0 because it is an isothermal process.
From kinetic theory:
Eint = f/2nRT
f is the degrees of freedom of the gas (constant)
n is the number of moles of gas molecules (constant)
R is a constant
The only thing that varies is T. If T doesn't change, neither does Eint.
2. Change in internal energy is 0 because it is an isothermal process.
From kinetic theory:
Eint = f/2nRT
f is the degrees of freedom of the gas (constant)
n is the number of moles of gas molecules (constant)
R is a constant
The only thing that varies is T. If T doesn't change, neither does Eint.