Difference in Radius, Difference in SpeedDate: 06/25/2002 at 15:24:41 From: Stacey Freeman Subject: Diameter effects rotational speed The diameter of a tire is 56 cm, and the valve stem is 17 cm from the center. What is the difference between the speed of a point on the tread of the tire and the speed of another point on the valve stem when the car wheel is moving at 5000 rpm? Can you show me the steps to solve this problem? Date: 06/25/2002 at 20:49:14 From: Doctor Ian Subject: Re: Diameter effects rotational speed Hi Stacey, Suppose we have a disc whose radius is 10 cm, and it's rotating at 1000 rpm. How fast is a point on the edge of the disc moving? The circumference of the disc is pi times the diameter, circumference = pi * (2 * 10 cm) Each time the disc rotates, a point on the edge travels a distance equal to the circumference of the disc. So in 1 minute, a point travels 1000 times the circumference: distance in 1 minute = 1000 * pi * (2 * 10 cm) = pi * 20000 cm = pi * 200 m or about 600 meters. So the speed of that point is 600 meters per minute. Can you take it from here? - Doctor Ian, The Math Forum http://mathforum.org/dr.math/ |
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