Force and Acceleration: Necessity of Force for Acceleration

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Discussion Overview

The discussion revolves around the necessity of force for acceleration, exploring the relationship between force, acceleration, and concepts such as kinetic energy and momentum. It includes references to Newton's laws and examines different interpretations of these principles.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant questions why force is necessary for acceleration.
  • Another participant cites Newton's laws, stating that an object in motion remains in motion unless acted upon by an outside force, implying that a force is needed to change uniform motion.
  • A different viewpoint suggests that acceleration involves a change in kinetic energy, which requires work done by a force, although this does not fully answer the "why" question.
  • One participant emphasizes the importance of distinguishing between resultant forces and kinetic energy, noting that uniform circular motion involves acceleration without a change in kinetic energy.
  • Another participant agrees with the previous point and introduces the concept of momentum change being equal to force times time, while also noting that work done during circular motion is zero due to the force being perpendicular to motion.
  • One participant expresses reluctance to change the original argument, suggesting that doing so could lead to unnecessary complications in the discussion.
  • Another participant briefly mentions inertia as a factor in the discussion.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between force, acceleration, and kinetic energy, with no consensus reached on the necessity of force for acceleration or the implications of kinetic energy in various motion scenarios.

Contextual Notes

There are unresolved nuances regarding the definitions of force, acceleration, and kinetic energy, as well as the implications of different types of motion, such as circular motion versus linear motion.

Bashyboy
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Why is it necessary that there has to be a force if there is an acceleration?
 
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Remember Newton's laws - an object in motion will stay in motion until acted on by an outside force. So, an object will normally be in a state if uniform motion - moving with constant velocity. If you want to change this uniform motion (accelerate it), you need to apply an outside force.
 
Acceleration implies a change in Kinetic Energy, that involves work being done on or by an object - which implies a force moving through a distance.

That isn't a true answer to "why" but there never is a complete answer to 'why' questions. All you can hope for is that an explanation helps you to put the unexplained thing in amongst enough familiar things that one is satisfied and it begins to make sense.
 
You must be very careful about the terms you use.
Newtons first law states that an object will remain at rest or move with constant velocity (constant speed in a straight line) unless it experiences a RESULTANT (unbalanced)force. If there is a RESULTANT force then there will be an acceleration.
It is misleading to associate Kinetic energy with acceleration. Uniform circular motion involves acceleration but no change in Kinetic energy.
Change in momentum but not KE
 
Last edited:
Good point.
So change the argument by saying Momentum Change is equal to Force times Time. The K.E. argument only works for motion in a straight line. The work done during circular motion is zero because the force and motion are at right angles.
You really have to be on your toes on this forum!
But I still stand by my statement about 'why' questions.
 
I am not going to be the one to 'change the argument'.
The original query was straight forward and the explanation is easy straightforward textbook stuff.
Changing the argument will result in yet another 50+ posts about nothing in particular.
 
Because of inertia.
 

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