Concept explainers
Using proportions A proportion is defined as an equality between two ratios; for instance,
Suppose that a small pizza costs a certain amount. How much should a larger pizza of the same thickness cost? If the cost depends on the amount of ingredients used, then the cost should increase in proportion to the pizza’s area and not in proportion to its diameter.
Let us rearrange Eq. (3.10) so the two variable quantities (cost and radius) are on the right side of the equation and the constants are on the left.
This equation should apply to any size pizza If r increases, the cost should Increase so that the ratio
For example, if a 3.5-in -radius pizza costs $4.00, then a 5.0-in radius pizza should cost
This process can be used for most equations relating two quantities that change while all other quantities remain constant.
The downward distance d that an object falls in a time interval t if starting at rest is
On the Moon, a rock falls 10.0 m in 3.50 s How far will the object fall in 5.00 s, assuming the same acceleration?
a. 14.3 m
b. 20.4 m
c. 4.90 m
d. 7.00 m
e. 100 m
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