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Frostbite Theater

Here's a Question! - Scales in Parallel

Place two scales side-by-side and stand on both of them. What will the scales read?

Announcer: Frostbite Theater presents... Cold Cuts! No baloney!

Joanna and Steve: Just science!

Joanna: Hi! I'm Joanna!

Steve: And I'm Steve!

Joanna: Here's a question for you...

Steve: Two digital scales are placed side by side and then are connected by a small bridge.

Joanna: Each scale is then tared so they both initially read zero.

Steve: A small steel bar massing 96.3 grams is placed on the bridge.

Joanna: What do the scales read?

Steve: Does the scale on the right read 96.3 grams and the scale on the left read zero?

Joanna: Does the scale on the left read 96.3 grams and the scale on the right read zero?

Steve: Does each scale read a smaller number that, when added together, equals 96.3 grams?

Joanna: Or, do they both read 96.3 grams?

Steve: Pause the video now if you'd like to think it over before we show you what happens.

Since the scales are being used in parallel, each scale only supports a portion of the bar, so each scale displays a portion of the bar's mass.

Joanna: But, if all the readings on all of the scales are added together, you'll get the bar's full mass.

Steve: Now, this is something you can try at home, even if you just have one bathroom scale. Substitute a block of wood or something for the second scale. Put one foot on the bathroom scale and your other foot on the block of wood and you'll see that the scale displays a fraction of your total weight.

Joanna: Thanks for watching. I hope you'll join us again soon for another question!

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