Uniform circular motion - origin of speed

In summary, the conversation discusses tangential speed in the context of uniform circular motion and how it relates to the centripetal force. The speed in this scenario is provided by the hand, which moves in an arc as the ball is brought to its final speed. The video provided a visual representation of the concept.
  • #1
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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  • #2
Notice what your hand is doing while you are bringing the ball from rest up to its final speed.
 
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  • #3
As I am bringing it to its final speed, my hand is moving in arc. So my hand is also providing the speed?
 
  • #4
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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  • #5
Awesome. Thanks a lot, your vector pic. really helped.
 

1. What is uniform circular motion?

Uniform circular motion is the motion of an object along a circular path at a constant speed. This means that the object is moving at the same speed at every point along the path.

2. What is the origin of speed in uniform circular motion?

The origin of speed in uniform circular motion is the centripetal force acting on the object. This force is directed towards the center of the circular path and causes the object to continuously change direction, resulting in circular motion.

3. How is speed calculated in uniform circular motion?

The speed in uniform circular motion can be calculated using the formula v = 2πr/T, where v is the speed, r is the radius of the circular path, and T is the time it takes for the object to complete one full revolution.

4. What is the difference between speed and velocity in uniform circular motion?

In uniform circular motion, speed and velocity are two different quantities. Speed is the magnitude of the object's motion, while velocity is the speed and direction of the object's motion. In circular motion, the speed remains constant, but the velocity changes as the direction of motion changes.

5. What is the role of inertia in uniform circular motion?

Inertia is the tendency of an object to resist changes in its motion. In uniform circular motion, inertia keeps the object moving in a circular path at a constant speed, even when there is a centripetal force acting on it. Without inertia, the object would not be able to maintain its motion and would fly off in a straight line.

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