Step-by-step explanation:
We are told to find the rotational speed needed for a 6.0 -nch grinding wheel to generate a linear speed of 4100fpm
To do so, we will use the given formula:

So, we are to solve for r, given that

So, if we make r the subject of the formula

Thus

If we are to round up our answer to the nearest hundred, we will have the rotational speed to be 2600 rpm