Back to the Future III (flick 1)

	Back to the Future III (1990)

	Concept featured in clip: Heat Pumps
	Location of clip:
	VHS: 0:39:00 DVD: ______ Play Flickclip Here (Quicktime)

Summary of clip: The scene opens with Marty and Doc in Doc’s blacksmith shop in the old west. There is a large machine working and making a lot of noise in the corner. We see Doc turning valves and taking measurements. All of a sudden a whistle blows and Doc asks Marty to turn a valve off. A clinking sound is heard and a single ice cube pops out of the machine. Marty states in amazement, “it’s a refrigerator.” Doc puts the ice cube in a glass of tea and asks Marty, “…ice tea?”

Connection of flickclip to the concept: This is a great clip to initiate a discussion on heat pumps and their everyday applications.

Suggestions to teachers:

1. Suggested questions for students when viewing the clip:

Pay attention to how the refrigerator is powered.

a. A refrigerator is a heat pump in reverse. How does a heat pump work? A diagram is helpful.

b. According to the second law of thermodynamics, work needs to be supplied to the heat pump. In the movie, where does this work come from? In real life, where does this work come from?

c. How does a refrigerator work? Can you locate key parts on the refrigerator?

d. What is the maximum efficiency of a refrigerator? Can it ever be 100% efficient? Explain.

e. How is a refrigerator similar to an air-conditioner? A diesel engine?