Physics Review Question

Unit: Mass
Year: 1992 Question#: 15
Question: Two rocks weighing 5 newtons and 10 newtons, respectively, fall freely from rest near the Earth's surface. After 3 seconds of free-fall, compared to the 5 newton rock, the 10-newton rock has greater:

(1 ) acceleration
(2 ) height
(3 ) momentum
(4 ) speed

What is this question really asking?

Explanation by: Joe W.

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Answer 1

INCORRECT- because of the neglection of air friction the two rocks would be accelerating at a same rate.

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Answer 2

INCORRECT- because they are falling at the same rate, their height's will be the same.

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Answer 3

CORRECT - even their velocity's are the same, the masses are different. Momentum is mass times velocity. p=mv so the momentum of the 10 newton rock will be greater than the momentum of the 5 newton rock.
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Answer 4
Because they are falling at the same rate, their speed's wil be the same.

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What's this question really asking?

As the 10N rock and the 5 Newton rock fall , what thing will be different after 3 seconds? return to top

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