# Chapter 1 - Introduction: Matter and Measurement - Additional Exercises: 1.67d

666223 miles/hour

#### Work Step by Step

This problem involves unit conversions, for the question gives you a number in one unit, in this case km/s, and asks for an answer in a different unit, miles per hour. $(\frac{29.783km}{s})\times(\frac{3600s}{hr})=107218.8 km/hr$ Above, notice that the unit seconds is both on the top and the bottom of a fraction. As a result, the unit seconds cancels out, leaving the resulting answer in km/hr. This step is legal because 3600s=1 hour, so multiplying by $(\frac{3600s}{hr})$ is like multiplying by 1, for any number divided by itself (except 0) is one. Using the same process and knowing that there are 1.609344 kilometers in a mile, the unit km/hr can be changed into mi/hr. $(\frac{107218.8km}{hr})\times(\frac{1 mile}{1.609344 kilometers})=66622.673586 miles/hour$ or $\approx66623mi/hr$.

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