I apologize if this seems much too "freshman", and may come across as annoyingly simple to some more trained or educated on this board. However I will ask the question anyways as I have failed to find an answer elsewhere.(adsbygoogle = window.adsbygoogle || []).push({});

Under Newton's Second Law of Motion, f=ma.

thus F = kg (m/s^2)

But when a person pushes against a wall like in the picture below, there is no acceleration, a=0.

The person and the wall have 0 velocity and 0 acceleration.

If a=0 then F=m(0), F=0

How can there be no force here (treating it mathematically according to the formula), when the person is exerting a force upon a body(the wall)?

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And secondly, if an object of a certain mass and velocity, is in motion but not accelerating,

Newtons second law also would calculate that there is no force according to the formula.

Say a 4 kg bicycle moving at a consistent velocity of 2 m/s, that has 0 acceleration.

http://www.theglobalintelligencer.com/images/bicycle.jpg

F=(4kg)(0) = 0

I know the momentum p, would equal p=(4kg)(2m/s) from p=mv.

But there is no momentum without a force being exerted upon the object. Force is coming from the rotation of the tire via the humans legs rotating a gear (translating an general up and down "force" into a rotational "force", giving the bicycle (the object) a momentum.

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# Difficulty understanding newtonian mechanics with stationary force

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