How does Newton's First Law show the existence of inertial reference frames?

Question

Newton merely stated the law of inertia as:

An object at rest stays at rest, and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

How does it prove the existence of inertial frames? I see no mention of it in the original law.

score 1 · Accepted Answer · answered Oct 05 '23 at 03:34

1

Newton's first law doesn't "prove" the existence of inertial frames; it defines inertial frames.

An inertial frame is one in which Newton's first law holds.

answered Oct 05 '23 at 03:34

Allure

20,501

but why didn't he(newton) define it in the law. did he assume that the law holds in inertial frames only? – Haria Kumar Oct 05 '23 at 03:35

How does Newton's First Law show the existence of inertial reference frames?

1 Answers1