Uniform circular motion - origin of speed

AI Thread Summary
In uniform circular motion, tangential speed is generated by the initial motion imparted by the hand, which moves in an arc as it accelerates the ball. The centripetal force provided by the string keeps the ball in circular motion, but the speed originates from the hand's movement. When the ball is first set into motion, the string is not perpendicular to the velocity, indicating that the hand contributes to the speed. Visual aids, such as videos, can clarify these concepts effectively. Understanding the relationship between the hand's motion and the ball's speed is crucial for grasping uniform circular motion.
compuser123
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I am having trouble understanding tangential speed as it applies to uniform circular motion and I would appreciate any help.

Say I have a ball on the end of a string that I hold with my hand and rotate at a constant speed. If the string provides the centripetal force and acceleration, where does the speed come from? what provides it?
 
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Notice what your hand is doing while you are bringing the ball from rest up to its final speed.
 
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As I am bringing it to its final speed, my hand is moving in arc. So my hand is also providing the speed?
 
compuser123 said:
As I am bringing it to its final speed, my hand is moving in arc. So my hand is also providing the speed?
Yes. As the ball is first brought into motion, the string is not perpendicular to the velocity.

Look at this video at about time 45 seconds.



Here is a snapshot soon after the ball is first set into motion.
upload_2018-1-16_12-31-12.png

You can see that the string is not perpendicular to the velocity.
 

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Awesome. Thanks a lot, your vector pic. really helped.
 
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