Question

Please help I'm really struggling!
How many miles/hour is 30 km/s?

Answer 1

1 km =0.625 miles
1s=1/3600 hour

Answer 2

I got 67,068 mile/hour, can someone check my answer?

Answer 3

1 km = 0.621371 mi (approx)
1 hr = 3600 seconds


\[\Large \frac{30 \text{ km}}{1 \text{ sec}}
\times
\frac{0.621371 \text{ mi}}{1 \text{ km}}
\times
\frac{3600 \text{ sec}}{1 \text{ hr}}\]



Notice how I set this up to where the "km" units cancel (one "km" unit up top, the other "km" down in the denominator. They divide to 1)

\[\Large \frac{30 \cancel{\text{ km}}}{1 \text{ sec}}
\times
\frac{0.621371 \text{ mi}}{1 \cancel{\text{ km}}}
\times
\frac{3600 \text{ sec}}{1 \text{ hr}}\]


Also, the "sec" units cancel as well for the same reason as the "km" units cancelling


\[\Large \frac{30 \text{ km}}{1 \cancel{\text{ sec}}}
\times
\frac{0.621371 \text{ mi}}{1 \text{ km}}
\times
\frac{3600 \cancel{\text{ sec}}}{1 \text{ hr}}\]

Answer 4

`I got 67,068 mile/hour, can someone check my answer?`

I'm getting a slightly larger number @steve816

Answer 5

I think it's because I rounded the miles to 0.62. But I understand it now! Thanks for the help!

Answer 6

no problem