Question #b625e

1 Answer
Jan 1, 2017

56.23 mph, rounded to two decimal places.

Explanation:

For circular motion we have the following equation connecting linear velocity v, of a point located at radius r, and rotating with an angular frequency ω

v=rω ........(1)
and ω=2πf .....(2)
where f is frequency of rotation.

Combining (1) and (2) we get
v=r(2πf)
Inserting given values after converting inch to mile and minute to hour

  1. For 14​-inch diameter blade: r=142=7 inch
    v14=(712×3×1760)(2π×3150160)
    v14=7×2π×3150×6012×3×1760
    =131.20 mph
  2. Similarly for 8​-inch diameter blade: r=82=4 inch
    v8=4×2π×3150×6012×3×1760
    =74.97 mph

Difference in linear velocity of two=v14v8
=131.2074.97
=56.23 mph, rounded to two decimal places.