# If an object's acceleration is zero, can its velocity be non zero?

Question:

If an object's acceleration is zero, can it's velocity be non-zero? Explain by giving an example.

My Attempt:

This doesn't make any sense at all. Via my teacher's solution she said "A Person walking at a steady pace along a straight sidewalk" $a = 0$ so $\therefore$ velocity is constant .. Well that may be the case, but I don't understand how my teacher saying "velocity is constant" answers the question at all?? The question asked if velocity can be a NON ZERO, and $0$ is considered a constant so what my teacher is saying is not really making any sense to me at all. What is an example where object's accelerration is 0 but it's $V_i$ or $V_f$ (velocity is a nonzero).. Wouldn't this be like idk, a ball that was thrown in space on the moon with a $v_i = 2m/s$ with a acceleration of 0? Would that be suitable?

• I don't understand. Your teacher's example is exactly an example of constant velocity that is non-zero. I mean, the person is walking, so how could their velocity be zero? Are you mixing up "velocity" with "change in velocity"? Because if acceleration is constant, the former can be non-zero, but the latter must be zero. Dec 4, 2015 at 1:11
• Yes more negative downvotes from the insane Physicists who have NO time for simple questions from us simpletons! Dec 4, 2015 at 1:36
• Should say for the rules for this website: "Poster must know the answer to his question before he posts it! Otherwise the poster will receive downvotes and people saying "BEGAST! What is wrong with you simpleton! How do you not know1?!" " Dec 4, 2015 at 1:37
• You've gotten downvotes (not just from physicists, I would imagine) because people think that this is a poor question for one reason or another. I can see this in part (though I didn't vote), because your attempt was not yours at all, but someone else's. That said, as the issue is conceptual, the typical homework-show-your-effort rationale might not be applicable. Dec 4, 2015 at 1:48
• I didn't downvote, but I don't entirely disagree with the downvotes. With a little more thought, you could've come up with this yourself. The fact that the answer is in any introductory physics textbook means that this question is not all that useful for the Physics.SE community. Consider that you could've just asked your instructor this question, and she would have been able to answer it quickly. I don't want to discourage you from asking questions, but note for instance that your "heavy crate" problem clearly violated the homework policy, which is why it was downvoted. Dec 4, 2015 at 1:51