PHY 1 THERMODYNAMICS

In a thermodynamic process, the change in the internal energy of a system is equal to:

• a) The heat added to the system

• b) The work done on the system

• c) The heat added to the system minus the work done by the system

• d) The heat added to the system plus the work done by the system

The first law of thermodynamics is a statement of the conservation of:

• a) Momentum
  

• b) Mass
  

• c) Energy
  

• d) Charge

When 200 J of heat is added to a system and the system does 50 J of work, what is the change in the internal energy of the system?

• a) 150 J
  

• b) 250 J
  

• c) 50 J
  

• d) 200 J

The mathematical expression for the first law of thermodynamics is:

• a) ΔU=Q+W
  

• b) ΔU=Q−W
  

• c) ΔU=Q×W
  

• d) ΔU=Q / W

If no heat is exchanged with the surroundings (adiabatic process), the first law of thermodynamics reduces to:

• a) ΔU=0
  

• b) ΔU=−W
  

• c) ΔU=Q
  

• d) ΔU=W

Which of the following statements best describes the first law of thermodynamics?

• • A) Energy cannot be created or destroyed, only transformed from one form to another.

• • B) The total entropy of an isolated system always increases.

• • C) The heat transfer in a system always equals the work done by the system.

• • D) The energy of the universe is constantly increasing.

When a gas expands in a cylinder, it does 50 J of work on the surroundings and absorbs 100 J of heat. What is the change in internal energy of the gas?

• • A) 50 J

• • B) 150 J

• • C) 100 J

• • D) 200 J

Which of the following processes is not a consequence of the first law of thermodynamics?

• • A) Perpetual motion machines of the first kind are impossible.

• • B) The internal energy of an isolated system remains constant.

• • C) Energy can be transferred between systems but the total energy remains constant.

• • D) The entropy of the universe tends to increase.

In an isothermal process, the change in internal energy (ΔU) is:

• • a) Equal to the work done on the system

• • B) Equal to the heat added to the system

• • c) Zero

• • D) Equal to the work done by the system

A system absorbs 500 J of heat and performs 200 J of work. According to the first law of thermodynamics, what is the change in the internal energy of the system?

• • A) 300 J

• • B) 700 J

• • C) 500 J

• • D) 200 J