Can anybody give an everyday example, that is, places where Newton's 3 laws of motion fail? I searched on this site, but it only answers for the 3rd law of motion
I recently read in a book, that Newton's law can fail in a circular motion. But it doesn't explain.
So, can anybody explain daily-life examples of the violation of Newton's 3 laws?
Newton's 1st law states that – An object at rest or moving with constant velocity in a straight line will remain so until an external force is applied to it.
I do not think this law will ever fail. But If you know a situation where it will fail, please tell!
Newton's 2nd law – Newton's second law of motion pertains to the behaviour of objects for which all existing forces are not balanced.
Newton's 3rd law – For every action, there is an equal and opposite reaction.
Can anyone explain the examples?
Best Answer
In general, Newton's laws of motion are true in inertial frames.
Consider you are in an elevator moving with a constant velocity downwards. Assume you have spring measure. Clearly here third law is valid. The spring is balancing the body's weight $mg$ using a force $kx$ upwards the body is applying a force $mg$ on the spring and the spring applies same force.
On the other hand, consider the elevator is moving with a constant acceleration $a$ upward, the extension of the spring is clearly not $\frac{kx}{m}$ and the spring is applying a force $m(g+a)$ on the body but body mass cannot apply anymore force than $mg$. The third law isn't quite valid. It gets valid if a pseudoforce $ma$ is assumed on the body in the opposite direction of acceleration.
Similarly we can say that in a circular motion (accelerated normal to the motion) third law of motion isn't quite valid unless we assume a pseudoforce in the outward direction called centrifugal force.