GCEPhysicsMeasurement and Units2019

The speed of light in vacuum is approximately $3.0 \times 10^{8} \ \text{m s}^{-1}$. Express this value in kilometres per hour (km h⁻¹).

A$1.08 \times 10^{9} \ \text{km h}^{-1}$CORRECT
B$8.33 \times 10^{5} \ \text{km h}^{-1}$
C$3.0 \times 10^{5} \ \text{km h}^{-1}$
D$1.08 \times 10^{12} \ \text{km h}^{-1}$
AI
Toaster Teacher
Why the answer is A, and why the others tempt you.
To convert m s⁻¹ to km h⁻¹, multiply by 3600/1000 = 3.6. So $3.0 \times 10^{8} \times 3.6 = 1.08 \times 10^{9}$ km h⁻¹. Option C is the speed in km s⁻¹ (a common error of only dividing by 1000), and option B results from dividing by 3.6 instead of multiplying.
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