You are watching: Can you have a negative speed

A vector points in a direction in space. A negative vector (or much more precisely "the negative of a vector") just points opposing way.

If i drive **from** house **to** occupational (defining my *positive direction*), then my velocity is **positive if ns go come work**, however **negative once I walk home** from work. It is all about direction watched from how I characterized my hopeful *axis*.

Consider an example where I end up further back than where I started. I need to have had actually *negative* net velocity to finish up going *backwards* (I end at a *negative position*). Yet only due to the fact that *backwards* and *forwards* are clearly defined together the *negative* and also *positive* directions, respectively, prior to I start.

So, does an unfavorable velocity exist? Well, because it is simply a issue of native that define the event, climate **yes**. An adverse velocity just way velocity in opposing direction 보다 what would certainly be positive.

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edited Jul 29 "20 at 14:10

answered Jun 15 "15 in ~ 13:08

SteevenSteeven

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From the math allude of view, you cannot have “negative velocity” in itself, just “negative velocity in a offered direction”.

The **velocity** is a 3-dimension vector, over there is no such point as a confident or negative 3D vector.

However, if you take into consideration the **velocity in direction $mathrmx$**, where $hatmathbfe_mathrmx$ is some unit vector offering a recommendation direction (say, "West"), climate the velocity “in direction $mathrmx$” is simply the scalar product the the velocity and $hatmathbfe_mathrmx$. This amount is a genuine number and also can be negative. If it is negative, that is equal to $-1 imes ext(velocity in direction -x)$: compute the velocity in the contrary direction, and also reverse the sign.

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edited Jun 16 "15 in ~ 17:05

leftaroundabout

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answer Jun 16 "15 in ~ 15:39

tarulentarulen

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I think among the main reasons that you have velocity is to isolate a specific direction of movement from her forward speed.

If you take trip North phibìc east, you can extract the speed at i beg your pardon you move eastwards by calculating her eastwards velocity (possibly 1/3 that your rate travelling NNE).

Negative velocities most likely arrived together a consequence of the reality that as soon as measuring a velocity, you have to specify a direction.

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answer Jun 16 "15 at 14:42

Ryan HancockRyan Hancock

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Negative and positive is arbitrary. If I identified north as positive, southern would be negative. If I defined south together positive, north would be negative. The signage merely serves to administer direction because that the velocity vector family member to some identified positive direction. All directions space arbitrary, and also you have the right to create any type of coordinate system for your occasions as lengthy as whatever is consistent with eachother.

We require this convention to explain position together a duty of time, because that example. If velocity was addressed to it is in positive, or similarly, if it to be scalar, mechanics would have actually some issues, due to the fact that it would mean things could never decelerate permit alone go backwards.

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answer Jun 19 "17 at 17:09

sangstarsangstar

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I will only think about one dimensional motion(motion along a single axis).The main objective the terms choose position and velocity is to define the motion of an item easily.

We specify velocity to it is in the rate of readjust of position .By convention we pick a fixed suggest (along the axis that motion) and also call it origin and also define an object"s position on the line based on the distance from this point. Again basic convention is that ranges measured towards right are positive and those measured towards left are an unfavorable (you deserve to use them reversed if girlfriend want).You can quickly see that in defining measurement of place this way we have actually covered every the points on the axis.In this conventions a place 2m means 2m ideal of origin and also a position -6m means 6m left of origin.

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Now friend would have heard the the authorize of velocity gives direction, but first of every directions are again simply references made by us .By trial and error we can make the end the physical meaning of + or - authorize . (By convention you speak to the direction in which the an adverse numbers increase an adverse direction(i.e left in this case) and also the direction in which optimistic number increase the confident direction (i.e ideal in this case)).

Example:-

You see an object an initial at 2m and then in ~ -3m after 5s . Friend say the it has moved in the direction of left or in the negative direction . Now by the definition of velocity girlfriend calculate adjust in position (-3-2)m = -5m (analysing you have the right to see the the "-" come out immediately as a an outcome of ours convention) and change in time = 5s.Dividing you get velocity together (-1m/s) or you have the right to say the the object was moving towards left at 1m/s .In this method you can number out what the negative sign means . That simply means that the motion is in the direction of the an adverse direction or towards left.(As you have the right to see our definitions and conventions aid us describe totally the motion of an item , both the rate at which it moves and also where the moves)