Video Transcript
What value of speed in kilometers per hour is equal to a speed of one mile per hour?
So we’re given a speed of one mile per hour and we want to know what this will be in units of kilometers per hour. To do this, we need to convert our units of distance from miles to kilometers. Our units of time can remain the same as they’re already in hours.
To answer this question, we’re going to take our initial value of one mile per hour and we’re going to multiply it by a fraction. Now, this fraction needs to meet two conditions. It has to be equal to one so that we’re not changing the value, and it has to change our units from miles to kilometers. We do that by having miles on the denominator, so that the miles down here cancel with the miles up here, and then kilometers in the numerator, so that the new distance value is in kilometers.
At this point, we need to recall that 1.6 kilometers is approximately equal to one mile. Therefore, we can put 1.6 kilometers and one mile into this fraction. This fraction now meets both of our conditions. It is equal to one, and we have miles in both the numerator and the denominator, so those two cancel. And we’re left with the units of kilometers per hour. So to express the speed of one mile per hour in kilometers per hour, we just need to calculate one times 1.6, which gives us 1.6. So one mile per hour is equal to 1.6 kilometers per hour.
