# The meaty part of centripetal acceleration

Discussion in 'Physics & Math' started by nicholas1M7, Jul 29, 2011.

1. ### nicholas1M7BannedBanned

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As I understand it velocity is constantly changing because direction but not magnitude is always changing. In order for a ball tied to a string to keep spinning it has to accelerate towards the center. Would it be correct to say that the fictitious force known as centrifugal force acts away from the center?

3. ### nicholas1M7BannedBanned

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How does acceleration work and relate to speed?

5. ### originHeading towards oblivionValued Senior Member

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Take a look at THIS.

7. ### nicholas1M7BannedBanned

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Thank you. Does anyone else have anything to add regarding my second question about acceleration and how it works with and relates to speed?

8. ### AlexGLike nailing Jello to a treeValued Senior Member

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Acceleration is a change in velocity as a result of a force applied..

It's a pretty stupid question.

9. ### nicholas1M7BannedBanned

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Oh gee thanks for the compliment. I'm looking for a deeper answer to how acceleration relates to speed. There is a deeper connection between acceleration and speed.

10. ### ChopsockyRegistered Member

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There's nothing deeper to it. Acceleration is defined as the rate of change in velocity of an object.

11. ### nicholas1M7BannedBanned

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There appears to be a deeper connection between the two and I will relay this soon.

12. ### ChopsockyRegistered Member

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I look forward to it.

ETA: I should point out that acceleration applies to velocity, which is a vector of speed and direction. So an object travelling in one direction at 50mph that then follows a curve to the right whilst maintaining that speed can be said to be accelerating in a lateral direction, even though it is still travelling at the same speed.

13. ### originHeading towards oblivionValued Senior Member

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When you apply a force to a mass it accelerates. The definition of this acceleration is a change in velocity. If the force is removed from the mass it will cease to accelerate and the velocity will be constant.

Do you have something to add to this?:shrug:

14. ### nicholas1M7BannedBanned

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Acceleration causes an increase in speed.

15. ### ChopsockyRegistered Member

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That's deep, man.

16. ### OnlyMeValued Senior Member

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Acceleration is a change in velocity (speed). As mentioned a few posts back, a change in direction while maintaining a constant velocity, is acceleration. It requires a change in the objects state of motion from a line to a curve.

Take a satellite in orbit. It may have a constant velocity and yet the gravitational force between the satellite and the Earth constantly changes its direction, pulling it from a straight line into an orbit around the planet. Here the force resulting in the acceleration is gravity.

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:bugeye:

18. ### OnlyMeValued Senior Member

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In an everyday setting this works fairly well. But think also about turning a corner in your car. You may stay at the same speed, changing only direction. A change in direction is also acceleration.

Acceleration is a change in speed and/or direction. As previously mentioned acceleration involves both velocity (speed) and direction. Any change in either or both is acceleration.

19. ### originHeading towards oblivionValued Senior Member

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And there you have it!

20. ### nicholas1M7BannedBanned

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Another way of saying this is that acceleration works with speed by increasing it.

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No, that's actually a bit childish because it does NOT "work with speed" - it simply "affects it". Or to put it even better, it "acts on it."

22. ### nicholas1M7BannedBanned

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It in fact works with speed by increasing it. I'll let you know more on why later when I learn more.

23. ### AlphaNumericFully ionizedRegistered Senior Member

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An object can experience acceleration and yet have constant speed. That's what circular motion is.

You seem to be under the impression you're telling us things we don't know. Not only are the things you're talking about taught to school children younger than 12 but you're getting the information wrong.

Acceleration alters velocity. If something experiences an acceleration then its velocity has changed, almost by definition. Whether or not the objects speed have changed is dependent upon the relative directions of the accelerating force and the velocity of the object. If an object moving with speed $\mathbf{v}$ experiences a force $\mathbf{F}$ then it will only experience a speed increase if $\mathbf{v}\cdot \mathbf{F} \neq 0$, ie they are not orthogonal. Can you prove why its orthogonality which matters?

You don't have the brilliant insight you think you do.