if a windshield wiper is 18 inches long, and it takes 1 second to trace out 1/2 of a revolution.?

Imagine what the question is about, draw a windshield and a wiper and the path the tip goes, when the windshield is in motion.

A revolution is the pattern the windshield is repeating, so let's assume it starts with a 1/2 circle to the right followed by half a circle back to the original position in rest, a total of two halfs or one full circle.

As a revolution is a complete circle, we can use the formula 2.pi.r for the distance the tip would travel, in numerals: 2 * 3,14 * 18" so a half revolution is 3,14 * 18"

As it takes one second to do this,

the speed of the tip in inches would be 3,14 * 18" / second

or if you like in minutes 60 * 3,14 * 18" / minute

or in hours 60 * 60 * 3,14 * 18" / hour

Now you can do the arithmetic, which is the least important part of the question.

Enjoy Math!

Anneke Schreuder

www.DyscalculiaServices.com

V = R(omega)

R=18

omega = (2pi/T)

T- time period for 1 revolution = 2 secs here.(cuz 1 sez for half revolution)

hence V = 18(2pi / 2)

V = 18pi = 56.52 inches/sec..

18 pi inches/sec

180deg/sec.....or.....1/2 revolution/sec.....or 56.5 inches/sec