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If we say "an object is at rest," can we also say "the object is moving at a constant velocity?"

Of course, the constant velocity would be zero, so it's mathematically sound. However, the wording throws us off, because we have specified that the object is moving, which should indicate a non-zero constant velocity. Besides that, how is the object moving if it is at rest?

Question source:

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closed as off-topic by Aaron Stevens, John Rennie, Emilio Pisanty, GiorgioP, tpg2114 Jul 29 at 1:26

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  • $\begingroup$ It's probably something your teacher overlooked. I wouldn't read too much into it. $\endgroup$ – Aaron Stevens Jul 27 at 4:20
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    $\begingroup$ how is 3 not a constant velocity? $\endgroup$ – Adrian Howard Jul 27 at 4:46
  • $\begingroup$ $v$ is the derivative of $s$, and since (3) is a linear graph, you are correct in saying that velocity is constant in (3). Notice that velocity is also constant in (1). $\endgroup$ – Landuros Jul 27 at 5:21
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    $\begingroup$ Was 1 and 3 an option? $\endgroup$ – garyp Jul 27 at 11:41
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    $\begingroup$ So you're asking whether zero is a constant? $\endgroup$ – WillO Jul 27 at 14:06
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If we say "an object is at rest," can we also say "the object is moving at a constant velocity?"

Not with respect to the same reference frame. I am sitting on a train moving at constant velocity with respect to the tracks. Am I "at rest" or am I moving at "constant velocity"? The answer is I am at rest in the reference frame of the train but I am moving at constant velocity with respect to someone on the tracks observing me through the train window.

As far as the diagrams go, just keep in mind that the velocity of the object is the rate of change in its position in the reference frame where $S(t)$ is measured, This is the derivative $\frac{dS(t)}{dt}$, which is the instantaneous slope of the $S(t)$ curve.

Hope this helps.

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