# Speed velocity and acceleration relationship

### knifedirectory.info: Motion: Velocity & Acceleration

Average speed is described as a measure of distance divided by time. Velocity can be constant, or it can change (acceleration). Speed with a direction is velocity . Speed and velocity are not the same thing: speed is a scalar, whereas velocity is a vector. Acceleration is a vector which shows the direction and magnitude of. Learn how to calculate speed, velocity and acceleration. The following equation shows the relationship between average speed, distance moved and time.

This is one of the essential differences between speed and velocity. Speed is a scalar quantity and does not keep track of direction; velocity is a vector quantity and is direction aware.

## Speed and Velocity

Determining the Direction of the Velocity Vector The task of describing the direction of the velocity vector is easy. The direction of the velocity vector is simply the same as the direction that an object is moving.

It would not matter whether the object is speeding up or slowing down. If an object is moving rightwards, then its velocity is described as being rightwards.

If an object is moving downwards, then its velocity is described as being downwards. Note that speed has no direction it is a scalar and the velocity at any instant is simply the speed value with a direction. Calculating Average Speed and Average Velocity As an object moves, it often undergoes changes in speed. For example, during an average trip to school, there are many changes in speed. Rather than the speed-o-meter maintaining a steady reading, the needle constantly moves up and down to reflect the stopping and starting and the accelerating and decelerating.

The average speed during an entire motion can be thought of as the average of all speedometer readings. If the speedometer readings could be collected at 1-second intervals or 0. Now that would be a lot of work.

### Displacement, velocity, acceleration

And fortunately, there is a shortcut. The average speed during the course of a motion is often computed using the following formula: In contrast, the average velocity is often computed using this formula Let's begin implementing our understanding of these formulas with the following problem: While on vacation, Lisa Carr traveled a total distance of miles.

Her trip took 8 hours.

What was her average speed? To compute her average speed, we simply divide the distance of travel by the time of travel. Lisa Carr averaged a speed of 55 miles per hour. Yet, she averaged a speed of 55 miles per hour. The above formula represents a shortcut method of determining the average speed of an object. Average Speed versus Instantaneous Speed Since a moving object often changes its speed during its motion, it is common to distinguish between the average speed and the instantaneous speed.

The distinction is as follows. Instantaneous Speed - the speed at any given instant in time. You might think of the instantaneous speed as the speed that the speedometer reads at any given instant in time and the average speed as the average of all the speedometer readings during the course of the trip. Moving objects don't always travel with erratic and changing speeds. Occasionally, an object will move at a steady rate with a constant speed.

That is, the object will cover the same distance every regular interval of time. If her speed is constant, then the distance traveled every second is the same.

Velocity and speed are very similar ideas, but velocity is a vectorand speed is not.

How would you draw an arrow to represent a vector? You can't know how to draw the vector if you only have one value either amount or direction.

In this example, you were never told about the direction. Velocity is the rate of motion in a specific direction. I'm going that-a-way at 30 kilometers per hour. My velocity is 30 kilometers per hour that-a-way. Average speed is described as a measure of distance divided by time.

## Velocity, Speed, and Motion... Oh My!

Velocity can be constant, or it can change acceleration. Speed with a direction is velocity. You will use a lot of vectors when you work with velocity.

Our real world example of navigation on the ocean used velocity for every vector. Velocity is a vector measurement because it has an amount and a direction. Speed is only an amount a scalar. Speed doesn't tell the whole story to a physicist. Think of it another way. If I tell you I'm driving north and ask you how long until we get to the city. You can't know the answer since you don't know my speed.

You need both values. One Moment in Time There is a special thing called instantaneous velocity. That's the velocity at a split second in time.

Above, we were talking about your speed and direction over a long period of time.