How can acceleration be perpendicular to velocity at any given time?

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Discussion Overview

The discussion revolves around the concept of acceleration being perpendicular to velocity, particularly in the context of circular motion. Participants explore the implications of this relationship and seek to clarify the underlying mechanics involved.

Discussion Character

  • Conceptual clarification
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants suggest that in circular motion, the velocity is tangential to the path while the acceleration points towards the center, leading to their perpendicular relationship.
  • One participant questions the direction of an object released from circular motion, implying a need for clarity on the effects of acceleration in such scenarios.
  • Another participant emphasizes that pulling an object causes acceleration, linking the action of pulling to the direction of acceleration in circular motion.
  • A participant explains that velocity is a vector with both direction and magnitude, and that acceleration can be decomposed into components that affect speed and direction differently.
  • One participant reiterates the idea that if speed is constant in circular motion, only the direction changes, which is aligned with the radius, thus indicating the direction of acceleration.

Areas of Agreement / Disagreement

Participants express various interpretations of the relationship between acceleration and velocity, particularly in circular motion. There is no consensus on all aspects of the discussion, as different viewpoints and clarifications are presented.

Contextual Notes

Some statements rely on assumptions about the nature of forces and motion, and the discussion does not resolve the complexities of vector decomposition or the implications of releasing an object in motion.

tatiana
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How can acceleration be perpendicular to velocity at any given time?
Is it because when ther is a circular path, there can be lines drawn tanget to the circular path that it follows? I don't understand!
 
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If you suddenly release an object rotating around a circle, which direction does it go?
 
When you make an object twirl on the end of a string, you're always pulling aren't you?

To pull something is to cause acceleration! (unless the object pulled on is fixed)
 
The direction of the velocity at any point is tangential to the circle at that point.To find the change of velocity between two points you can perform a vector subtraction of the velocities at the two points and to find the average acceleration between the points divide the velocity change by the time.To find the instantaneous acceleration consider the limit where the angular separation between the points approaches zero.You will find that the direction of the acceleration is towards the centre of the circle.
 
tatiana said:
How can acceleration be perpendicular to velocity at any given time?
Is it because when ther is a circular path, there can be lines drawn tanget to the circular path that it follows? I don't understand!

This is because the velocity at a particular instant is directed along tangent at that point while the acceleration is always directed towards the center of the circle. Clearly these two are perpendicular to each other.
 
Remember that velocity is a vector quantity and acceleration is the time rate of change of velocity. Since velocity is a vector it has both direction and magnitude; therefore a change in velocity can be a change in magnitude (speed) or a change in direction.

You can break any acceleration vector into components along the line of velocity and perpendicular to the velocity. The component of acceleration along the direction of velocity changes the speed, and the perpendicular component changes the direction.
 
tatiana said:
How can acceleration be perpendicular to velocity at any given time?
Is it because when ther is a circular path, there can be lines drawn tanget to the circular path that it follows? I don't understand!
I could put it yet another way:
Acceleration is rate of change of velocity. Velocity is speed and direction. If the speed is constant (it's just going round and round), it is only the direction that is changing for a circular path. The change of direction is along a radius so that is the direction where the acceleration is.
Also, if the string is totally flexible, then it can ONLY pull along a radius. That means that the only possible direction of acceleration must be along a radius as it's the only direction that any force is acting.
 

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