# Conceptual Question (Rotational Kinematics)

#### Dmt669

A thin rod rotates at a constant angular spped. COnsider the tangential spped of each point on the rod for the case when the axis of rotation is perpendicular to the rod (a) at its center and (b) at one end. Explain for each case whether there are any points on the rod that have the same tangential speeds

This came from Cutnell and Johnson Physics 5th edition, does anyone know where I could find answer to thier conceptual quesitons, math would be nice too ,thanks

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#### Andrew Mason

Homework Helper
Dmt669 said:
A thin rod rotates at a constant angular spped. COnsider the tangential spped of each point on the rod for the case when the axis of rotation is perpendicular to the rod (a) at its center and (b) at one end. Explain for each case whether there are any points on the rod that have the same tangential speeds

This came from Cutnell and Johnson Physics 5th edition, does anyone know where I could find answer to thier conceptual quesitons, math would be nice too ,thanks
Usually conceptual questions are answered by thinking about them. They test whether you understand the concepts. Finding answers from a source other than your mind defeats their purpose.

(Assume that the 'points' being referred to have a single co-ordinate being the distance from the axis of rotation). So the question is really asking, are there two locations on the rod that have the same tangential speed? Given that the rod has a constant angular speed, what determines tangential speed? To answer this you have to know the mathematical expression for tangential speed: how fast would an ant a distance d from the axis be moving if the rod is moving at constant angular speed $\omega$?

Then apply this to situations a) and b).

AM

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