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If I am having a graph of displacement versus time and at time = 0 second, the displacement of an object is 10 metres.

I need to know: what is its initial velocity?

Is it 10 m/s?

(Note that the average velocity is given: 20 m/s)

Also, its a rectilinear motion and has constant (0$m/s^2$ ) acceleration throughout.

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closed as off-topic by Kyle Kanos, peterh, heather, Jon Custer, M. Enns Aug 7 '17 at 0:49

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  • $\begingroup$ The initial velocity may be 0. Graph will start from y axis at point 10m instead of 0. $\endgroup$ – Wrichik Basu Aug 6 '17 at 12:50
  • $\begingroup$ @WrichikBasu Yes, graph starts at y=10m, but why initial velocity may be 0? $\endgroup$ – Ravi Prakash Aug 6 '17 at 12:51
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    $\begingroup$ See, that was a guess. I believe that your question is unclear, and you need to put up more info on what type of motion you're analysing and similar facts. On your current question, I cannot say more. Others will surely help you, if they can. $\endgroup$ – Wrichik Basu Aug 6 '17 at 12:54
  • $\begingroup$ @WrichikBasu Is the question clear now? Or more info needed?? $\endgroup$ – Ravi Prakash Aug 6 '17 at 12:56
  • $\begingroup$ Is it possible to upload a picture of the graph? $\endgroup$ – Wrichik Basu Aug 6 '17 at 13:05
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If the acceleration is $0$ then the velocity does not change and the instantaneous velocity is the average velocity, i.e. $20m/s$. The graph of $x$ as a function of $t$ will be a line with slope $20$, i.e. $x=20 t + x_0$, and going through the point $(x,t)=(10,0)$

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As you have stated that it's a rectilinear motion and given acc=0, this implies that

average velocity = instantaneous velocity

because the body neither accelerates nor decelerates.Only when there is a acc/dec there is a change in velocity. So it's initial velocity = average velocity.

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