Terms to Know
Solving
100

What objects convert thermal energy into mechanical work?

Heat engine

100

Which system cannot exchange energy nor matter with its surroundings?

Isolated system

200

In all processes, _____________ must increase or remain the same.

Entropy

200
350 J of work is done on a system.   90 J of thermal energy is lost by the system.  What is the change in internal energy of a system?

260 J

300

What does a heat pump do?

Does work to move thermal energy from a cold reservoir to a hot reservoir


Reverses the Carnot cycle

300
A heat engine has a cold reservoir at 974 oC.  If the efficiency is 49%, what is the temperature of the hot reservoir?

1909 oC

400
Describe the four steps of the Carnot Cycle.

The system absorbs thermal energy (QH) from the hot reservoir.


The system expands adiabatically (work is done on the piston)


The system gives up thermal energy (QC) to a cold reservoir.

 

The gas adiabatically compresses further

400
A gas at 45 L and 399 Pa expands to 90 L and 200Pa.  What is the work done? Is it on or by the gas?

13477.5 J


Work is done by the gas

500

State the Four Laws of Thermodynamics

Zeroth - If two systems are in thermal equilibrium with a third system, then they must be in thermal equilibrium with each other

First - Energy cannot be created or destroyed, only transferred or transformed

Second - Thermal energy flows from an area of higher concentration to an area of lower concentration

Third - absolute zero is unattainable

500

A gas is used to move a piston.  Originally, the gas is at 15 L and 400 Pa.  Then, the volume is decreased to 3 L and the pressure is increased to 1000 Pa.  Then, the pressure decreases to 400 Pa while keeping the volume the same at 3 L.  Finally, the volume expands to 15 L while keeping the pressure at 400 Pa.  What is the work done?  Is it on or by the gas?

3600 J


Done on the gas

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