Please help me with the question in the description

Question

In making one revolution a bike wheel travels 1.8m. If the bike is travelling at 24km/h, how fast is the wheel turning in revolutions per minute?

Answer 1

It is not necessary to have a wheel in this problem.  Most people understand speed in feet/minute or yards per minute.  This problem simply asks “How many 1.8m-units per minute?”

Thus, this is merely a units conversion problem.  To convert units without changing the value, we use the multiplicative identity(that is, 1).

 

The information we need:

  1 km = 1000 m

  1 hr = 60 min

 

Now convert units:

   (24 km/hr)*((1 rotation)/(1.8 m)) 

   ((24 km)/(1 hr))*((1 rotation)/(1.8 m)) * 1

   ((24 km)/(1 hr))*((1 rotation)/(1.8 m)) * ((1 hr)/(60 min)) * ((1000 m)/(1 km))

              [note: km and hr and m cancel, leaving rotations/min]

   (24)*(1/1.8)*(1/60)*(1000) rotations/min    [note: written this way to paste into Excel]

   222.22 rotations/min

Answer 2

24km/h = 24000 m/h

 

24000/1.8 = 13,333.33 rotations per hour

 

divide by 60 (minutes in an hour) to get 222.22 rotations per minute

 

Hope this helps, Kevin!