An inertial frame of reference is described as being a frame of reference in whi
ID: 1392271 • Letter: A
Question
An inertial frame of reference is described as being a frame of reference in which the first law of Newton (the law of inertia) holds. This means that all events as described with respect to this frame of reference must have a zero net force acting on it and therefore traces a straight line with a uniform non-translatory motion. But, I have read in some books, especially "Introduction to Special Relativity" by the well-known Robert Resnick, wherein his definition of an inertial frame of reference also refers to such a frame of reference as being an unaccelerated system. This is where I am confused.
How can we describe a frame of reference as being unaccelerated if we occupy the frame of reference itself? No mechanical experiment conducted solely confined to a single frame of reference can determine the absolute motion of the frame of reference relative to another frame of reference. All that can be understood is that there is a certain uniform relative motion between frames of reference and no more. Is Robert Resnick saying that the inertial frame of reference is unaccelerated with reference to another frame of reference?
Explanation / Answer
all events as described with respect to this frame of reference must have a zero net force acting on it
This is wrong: there may exist nonzero forces in an inertial frame of reference. These have to obey Newton's laws. If the forces do not obey Newton's laws in your frame of reference, then it is not an inertial frame.
Newton's laws are correct only in an inertial frame of reference. What is an inertial frame of reference? One in which Newton's laws are correct.