How do you convert 240 miles per hour to feet per second?

Hint: We need to understand the given units of measurement and the relationship between them to convert from the first form to the second form. We can solve the problem by converting the given unit into the standard unit of measurement.

Complete answer:
We know that the two given units – miles per hour and the feet per second – are the units of measuring the speed of a moving object. We know that we use these units when we consider the number of miles of motion of a body in an hour or the number of feet covered by the body in a second.
We can easily convert the given quantity of 240 miles per hour into the standard unit of measurement of speed i.e., the meters per second which can be easily converted to the unit of feet per second much easily.
We know that one mile is equivalent to almost 1.60934km. Also, an hour can be easily converted to seconds. So, we get the speed of the object in meters per second as –
\[\begin{align}
  & 1mile=1.60934km \\
 & \Rightarrow 1mile=1609.34m \\
 & 1hr=60\times 60s \\
 & \Rightarrow 1hr=3600s \\
 & 240milesh{{r}^{-1}}=240\dfrac{1609.34m}{3600s} \\
 & \Rightarrow 240milesh{{r}^{-1}}=240\times 0.4470m{{s}^{-1}} \\
 & \therefore 240milesh{{r}^{-1}}=107.28m{{s}^{-1}} \\
\end{align}\]
Now, we can convert this to feet per second. We know that one foot is equivalent to 12 inches and one inch is equivalent to 2.54 cm. Using this relation, we can find the speed in feet per second as –
\[\begin{align}
  & 1foot=12inches \\
 & 1inch=2.54cm=0.0254m \\
 & \Rightarrow 1foot=12\times 0.0254m \\
 & \Rightarrow 1foot=0.3048m \\
 & \therefore 1m=3.281ft \\
 & \text{given,} \\
 & 240milesh{{r}^{-1}}=107.28m{{s}^{-1}} \\
 & \Rightarrow 107.28m{{s}^{-1}}=107.28\times 3.281ft{{s}^{-1}} \\
 & \therefore 240milesh{{r}^{-1}}=351.986ft{{s}^{-1}} \\
\end{align}\]
So, 240 miles per hour is equivalent to almost 352 feet per second.
This is the required relation and the solution.

Note:
The different units of speeds are often helpful in comparing the speeds of different bodies in different situations. We can compare the speed of an aeroplane to that of an electron in a conductor by converting it into one and more sensible unit for ease.