Question

Ok new mothersucking question....
help please :)
Convert 50 ft per s to mph.

5280 ft = 1 mi

Round to the nearest hundredth.

Enter your answer in the box.

Answer 1

This isn't too bad. Think of units you can cancel.

The way I convert my units is through a method called "dimensional analysis" as my teachers would call it, or the "train track method", or whatever.

So this is what you have (50 feet per s)
\[\frac{ 50 ft}{ s }\]
as In for every 50 feet, you have 1 second.

Now, mph in essence means > mile(s) per hour.

\[\frac{ mile}{ hour }\]

We know that in 5280 ft = 1 mile

So we mak a ratio out of the 5280 = 1 mile, to where we can cancel the unit ft on our 50 feet per s
\[\frac{ 50 ft }{ s } * \frac{ 1 mile }{ 5280 ft }\]

The feet cancels out and we are left with
\[\frac{ 50 * 1 mile }{ 5280*s }\]
= \[\frac{ 50 miles }{ 5280 s }\]
if we simply that we get: 0.00947 miles per s

Now we are not done yet because h (hours) in the denominator and not s. right now we still have s in the denominator.

We know that in 1 hour = 60 min
and in 1 min = 60 seconds

So you do the same thing you did above, except we have to do it twice:
\[\frac{ 0.00947 miles }{s } * \frac{ 60s }{ 1 minute } * \frac{ 60 minutes }{ 1 hour }\]

the seconds cancel out since you have an 's' in the numerator and the denominator, minutes also cancel out for the same reason, and you're left with 1 hour.

Multiply out and you get

\[\frac{ 34.092 miles}{ hour } \]
or or 34.092mph

Answer 2

ooh thank you i will write this down

Answer 3

You're welcome :)