What's the difference between speed and velocity?

Quick answer:

Speed is how fast an object is moving, while velocity is the rate at which an object changes position in a certain direction. Speed is calculated by the displacement of space per a unit of time. Velocity is calculated by the displacement of space per a unit of time in a certain direction. In short, velocity factors in direction, but speed does not.

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The short answer is that velocity is the speed with a direction, while speed does not have a direction.

Speed is a scalar quantity—it is the magnitude of the velocity. Speed is measured in units of distance divided by time (e.g., miles per hour, feet per second, meters per second, etc.).

Velocity is a vector quantity—when giving the velocity we must specify the magnitude (the speed) and the direction of travel. For example you might drive 100km/hr (the speed) in a northerly direction.

This is analogous to the difference between distance (a scalar quantity) and displacement (the distance with direction).

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This is a great question and I can see your confusion. There are similarities, but there are also differences. I will give you a definition of each and then provide an example.

Speed refers to how fast an object is moving. It is calculated by the displacement of space per a unit of time.

Velocity refer to the rate at which an object changes position in a certain direction. It is calculated by the displacement of space per a unit of time in a certain direction.

These definition might sound the same, but there is a crucial difference. It deals with direction. Velocity deals with direction and speed does not. Let me give you an example.

If you were driving at 50 miles per hour to get to a store, you would say that your speed is 50 miles per hours. If you were driving in a circle and ended at the same place, you would say that your velocity is zero, because there was no directional gain. The key to remember is that velocity is a vector, which means there is a directional component.

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Speed is the ratio of distance traveled to the time elapsed.

i.e. speed = distance/time

whereas, velocity is the ratio of displacement to the time elapsed.

i.e., velocity = displacement/time

Now, displacement can be 0, but distance traveled cannot be. Think about what happens when we throw a ball up in the air and it falls down. It has certainly traveled certain distance; however its displacement (difference between initial and final position) is zero (as the ball started from ground level and came back to it). Thus, in this case, velocity is zero, speed is not.

Also, speed is a scalar quantity, i.e. it only has magnitude. On the other hand, velocity is a vector quantity, since it has both the magnitude and direction. 

Both of them are measured in the same units of length per unit time.

Hope this helps.

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What is the difference between average speed and average velocity?

Speed is speed, or how fast something is going, while velocity is speed or how fast something is going in a specific direction. Average speed is the speeds added up and divided by number of speeds, and you do the same tning to calculate average velocity.
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What is the difference between average speed and average velocity?

Speed is the rate of change in position in a given amount of time.  Thus, speed is measured in units of meters/second (m/s), kilometers per hour (km/hr) and more familiarly miles/hour (mph).  Average speed is then the total distance traveled divided by the total time spent traveling.

Velocity has identical units to speed but the direction of motion must also be specified.  In addition, velocity looks at the displacement (the shortest distance from the start of the motion to the end of the motion).  This can lead to some interesting differences between average speed and average velocity.

Consider, for example, a runner on a 400 meter track.  Suppose the runner completes exactly 4 laps in 6 minutes.  Their average speed is then 1600 m/360 s or 4.44 m/s.  However, there average velocity is zero!  This is because their displacement is zero.

Another example would be if someone drives 300 m east, then 400 m north in a total time of 5 minutes.  Their average speed is 700 m/300 s or 2.33 m/s.  However, their displacement is 500 m from where they started.  Therefore, their average velocity is 500 m/300 s or 1.67 m/s @ 53.13 degrees north of east.

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What is the difference between average speed and average velocity?

The basic difference is that speed is a scalar quantity, and velocity is a vector quantity; basically, direction matters when talking about velocity, and it doesn't when we are talking about speed. Speed is how fast something is moving--the rate at which a distance is covered. Velocity measures how fast something changes position. Think of it this way: if you run 100 meters in 10 seconds then immediately run back to your starting point in 10 seconds, your average speed is 10 meters per second--you have covered 200 meters in 20 seconds. Your average velocity is zero--you haven't changed your position after 20 seconds.

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What are the similarities and differences between speed and velocity?

Speed is the distance covered by a moving object in a single unit of time, for instance 1 second. On a distance-time graph, speed is the gradient of the graph, or the derivative of the equation of distance against time with respect to time.

Speed, however, has no direction associated with it. It is said to be a scalar quantity as it has zero dimensions. The speed of a moving object is calculated by measuring how far from a starting point A the object gets (say it gets to point B) in 1 unit of time. If A and B are say 3m apart, then we know that the object is moving at 3m per second say. To calculate speed, we only need to know how far A and B are apart in 3D (Euclidean) space (the space that we experience around us that is), or in 2D space if we are considering travel on the flat only. We do not need to know what direction B is from A.

Whereas, velocity has both direction and magnitude (as the character Vector says in Despicable Me), and not just magnitude as is the case with speed. It is said to be a vector quantity because it has more than zero dimensions. So velocity has a speed associated with it, measuring how far the object gets from point A (say it gets to point B) in 1 unit of time, but also has a direction associated with it. For velocity, unlike speed, we need to know what direction B is from A. For this, we could say how many degrees the direction of B from A is off North - if it is directly East of A, this would be 90 degrees clockwise off North; or, we could say what direction to go in in gridded 3D (or 2D if on the flat plane) space - say, to get to B from A go sideways 2, forwards 3 and upwards (towards the sky) 1, which we could write as a vector (2,3,1). Velocities are usually written in speed and vector form, so we would say the object is travelling at eg 3m per second in the direction (x,y,z) eg (x,y,z) = (2,3,1). The length of the vector determines the number of dimensions of space we are travelling in, which in the real spatial world is at most 3.

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What is the difference between speed and velocity?

Speed is defined as the rate of change of motion of an object. In other words, it is the ratio of distance traveled to time taken.

speed = distance traveled by the object / time taken for the journey

In comparison, velocity is the rate of change of position of an object. In other words, it is the ratio of displacement to the time taken by an object.

Velocity = displacement of the object / time taken

Speed is a scalar quantity and only has a magnitude. In comparison, velocity is a vector quantity and has both magnitude and direction. 

Speed is dependent on the path taken by the object, since it is needed to determine the distance. Velocity is independent of the path taken by an object, since it depends on the displacement (distance between initial and final position of an object).

Hope this helps.

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What is the difference between speed and velocity?

Many people use the terms more or less interchangeably (often using "velocity" when they mean "speed" but want to sound more impressive), but there is a very simple but vital difference between the two.

The easiest way to explain the difference between speed and velocity is that speed is a number, while velocity is a vector. Speed is the magnitude of velocity.

Speed has no direction associated with it; it's just a value, like 50 m/s or 60 mph.

But velocity has a direction, and is generally expressed in one of two forms: Components in x, y, and z, like this:
<30 m/s, 40 m/s, 0 m/s>

or magnitude and direction, like this:
50 m/s at 53 degrees north of east.

I've chosen these so they are in fact the same vector. This is analogous to the difference between rectangular (Cartesian) coordinates and polar coordinates.

Speed is the magnitude of direction; the above velocity vector has a magnitude of 50 m/s, so the speed is 50 m/s.

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What is the difference between speed and velocity?

The speed of an object can be calculated if you know the distance that was traveled divided by the time it took to get there. Units can be miles per hour or kilometer per hour for example. However, velocity is the measurement of the rate and direction of change of a given object in motion. For instance, if a person is running 2 miles per hour, that is her speed. However, if she is running 2 miles per hour southwest, that is her velocity.

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What is the difference between speed and acceleration?

Speed is given as a ratio of distance travelled over time and is a scalar quantity, that is, it has only magnitude and no direction. Which means that irrespective of whether the object rotates around a fixed point or moves away from it in a straight line, it can have the same speed, provided it travelled the same distance in same time. Velocity is a vector quantity that denotes the displacement of an object per unit time. It has both a magnitude and a direction. Comparing with the speed, velocity can be zero even if the object has travelled some distance (that is has a non-zero velocity), if the displacement is zero. The rotation around a fixed center is a good example of this scenario. Both, the velocity and speed have units of length over time, that is, meter per second or km per hour. 

Acceleration is the rate of change of velocity and has units of length per time squared, that is, meter per second squared or km per hour squared. The most common example of acceleration is acceleration due to gravity (g), which ensures that all the objects falling down accelerate at the same value. Also, acceleration is a vector quantity unlike speed (which is scalar).

Hope this helps.

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Distinguish between speed and velocity.

This is a good question.  Speed and velocity are not the same thing; however, most people incorrectly use the two terms interchangeably.  Speed is a scalar quantity.  That means it can be described by a numerical value alone.  Speed simply refers to how fast an object is moving.  It is a rate of travel.  

On the other hand, velocity is a vector quantity.  Vector quantities are quantities that are described by both a magnitude (numerical value) and a direction. Some teachers tell students that velocity is "direction aware."  That just means you must include the direction of travel.  

Here is an example of speed: 65 miles per hour.

Here is an example of velocity: 65 miles per hour, west.  

It might seem like a small difference, but knowing the direction of movement is important.  For example, if I told you that two trains were on the same track and moving at a speed of 65 miles per hour, you have no idea if they are moving toward each other, away from each other, or in the same direction. If both trains are on the same track and they both have a velocity of 65 miles per hour, south, then there is no cause for concern.  

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