# Newton's laws and non inertial frame of reference

1. Jun 16, 2009

### raknath

Hi all

Why do we actually say that newton's laws do not hold for non inertial frames. can you folks give me an example of how newton's laws collapse in an non inertial frame(if they do at all)

2. Jun 16, 2009

### A.T.

In accelerated frames objects with no forces acting on them accelerate. So you have to introduce "http://en.wikipedia.org/wiki/Fictitious_force" [Broken]" to make Newtons laws work again.

Last edited by a moderator: May 4, 2017
3. Jun 16, 2009

### maverick_starstrider

It's not that newton's laws fail it's just that in a non-inertial reference frame one cannot consider their system to be 'free of external forces' and things get complicated. However, it can all be worked out using newton's laws you just have to be very careful.

4. Jun 16, 2009

### Staff: Mentor

And the fictitious forces do not obey Newton's 3rd law, so in patching the 1st and 2nd laws that way the 3rd law doesn't work any more.

Last edited by a moderator: May 4, 2017