An automobile windshield wiper 10 inches long rotates throug

An automobile windshield wiper 10 inches long rotates through an angle of 60°. If the rubber part of the blade covers only the last 9 inches of the wiper, find the area of the windshield cleaned by the wiper.

The earth rotates through one complete revolution every 24 hours. Since the axis is perpendicular to the equator, you can think of a person standing on the equator as standing on the edge of a disc that is rotating through one complete revolution every 24 hours. Find the angular velocity of a person standing on the equator.

Solution

These are 2 questions and should be posted separately. I will answer only first of them as per chegg policy.

1.

Area formed by the sector with angle at center A and radius R = (Angle/360)*Pi*r^2

Area by 10 inches and 60 angle = (60/360)*pi*100

Area by 1 inches and 60 angle = (60/360)*pi*1

cleaned area is just due to the rubber part and non rubber part (1 inch) will not clean any area so that will be subtracted from it)

Area cleaned = Area by 10 inches - area by 1 inch = (60/360)*pi*100 - (60/360)*pi*1

Area cleaned = (60/360)*pi*99 = 99pi/6 = 16.5 pi = 51.85 inch²