Question

Which is the more reasonable measurement of the distance between the tracks on a DVD: 7.4 ⋅ 10−4 mm or 7.4 ⋅ 104 mm? Justify your answer.

Answer 1

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Explanation:

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Answer 2

A- 7.4 ⋅ 10−4 mm

Explanation:

Well, to solve this problem, we must convert the number and / or the units in a more imaginable one.

We are given two choices:

a. 7.4 x 10^-4 mm

b. 7.4 x 10^4 mm

Converting the units and numbers into meters and general form, respectively. (What is meant by general form is not to write it in scientific notation).

a. 7.4 x 10^-4 mm (1 m / 1000 mm) = 0.00000074 m

b. 7.4 x 10^4 mm (1 m / 1000 mm) = 74 m

Now comparing the two values above, what do you think is the distance between the tracks on a DVD? Definitely NOT 74 m or else the DVD is extremely big. Therefore the correct is the smaller one.