Revolutions and radius of wheel

AI Thread Summary
To determine the radius of a wheel when a string is pulled, the relationship between the length of the string and the wheel's circumference is essential. The circumference can be calculated using the formula C = 2πr, where r is the radius. The distance the string is pulled corresponds to the number of revolutions multiplied by the circumference. The confusion arises from equating displacement with revolutions; instead, focus on the relationship between the string length and the wheel's rotation. Ultimately, the radius can be found by rearranging the circumference formula based on the given parameters.
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Homework Statement



A string is wound tightly around a wheel. When the end of the string is pulled through a distance of ? cm, the wheel rotates through ? revolutions. What is the radius of the wheel?




Homework Equations





The Attempt at a Solution



i'm confused about this simple problem because i believed that displacement and revolutions were the same for theta in a kinematics problem like this: theta = 1/2(w0 + w)t

what equation would I use to solve such a problem.
 
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All you need is the relationship between circumference and radius. You get the circumference from the length of string pulled and the number of revolutions.
 

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