Exploring the Relationship Between Speed and Diameter in Wheel Rotation

[cinemacell]

Does an inside of a wheel spin faster than the outer diameter of the wheel?

Isn't this how gears work?

 

[Fewmet]

Does an inside of a wheel spin faster than the outer diameter of the wheel?

Isn't this how gears work?

Welcome to Physics Forums.

Like many questions, the answer varies with precise definition of the terms. What you mean by "faster"? Is passing over more distance per unit time (like more meters per second)? Or is it rotation through bigger angle per second (degrees per second)?

 

[BruceW]

At every part of the wheel, it is rotating at the same rate. i.e. $\omega$ is constant every part of the wheel. We also have:
$$v_{tangential} = \omega r$$
where r is radius from centre of wheel, so yes, the outer part of the wheel is moving faster.

The principle behind gears is that high gears require a greater torque to turn, but then they move the main bicycle wheel further round per pedal.

 

[Drakkith]

Does an inside of a wheel spin faster than the outer diameter of the wheel?

Isn't this how gears work?

Actually the outside of a wheel has a faster velocity than the inside. You can see this by putting a mark or something on the inside and outside of a wheel and observing while it turns.

I tried to do a paragraph on gears, but I don't know enogh terminology with gears and such to explain it well.

 

[cinemacell]

@Fewmet
To try to more precisely define the terms within my question: I guess what I'm trying to ask whether the speed inside a circle travels faster in terms of distance covered.

@BruceW
Do you mean to say that in order for both inner point and outer point of the wheel to arrive at the same destination at the same time - the outer point located at the outer of the wheel has to move faster in order to 'catch up' or be in sync to the inner point - which moves less to cover the same distance travelled?

@Drakkith
I would love a layman's explanation on gears being a layman myself.


Many many thanks for the replies guys.

 

[BruceW]

Think about it like this: to do one rotation, a point near the centre of the wheel travels a much smaller distance than a point further out. Both parts must do 1 rotation in the same amount of time because the wheel is rigid. Therefore the point further from the centre has a greater speed.