# How do I calculate speed in a velocity-time graph? Displacement-time graph?

• kimi8
In summary, the speed can be determined from a velocity-time graph by calculating the slope of the line. The units for speed on a velocity-time graph are typically meters per second (m/s) or kilometers per hour (km/h). The distance traveled can be calculated from a velocity-time graph by finding the area under the curve. Yes, you can calculate speed from a displacement-time graph. On a velocity-time graph, speed and velocity are represented by the same line, but velocity also includes the direction of motion.
kimi8

## Homework Statement

How do I calculate speed in a velocity-time graph? And in a displacement-time graph?

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## The Attempt at a Solution

I'm quite at a lost at how to calculate these =S
Any help is appreciated.

If your graph is V(t) vs. t then isn't the graph at any point the V at that particular t?

For displacement and time, what is the definition of speed? Change in displacement for a change in time? And if you examine an extremely small time change at a point then what is that?

In order to calculate speed on a velocity-time graph, you can use the slope of the line. The slope represents the change in velocity over a specific time interval. The formula for slope is rise over run, or (change in y)/(change in x). In this case, the change in y would be the change in velocity and the change in x would be the change in time. So, the speed at any given point on the graph would be equal to the slope of the line at that point.

In order to calculate speed on a displacement-time graph, you can use the same method as above. The only difference is that instead of using the change in velocity, you would use the change in displacement. So, the speed at any given point on the graph would be equal to the slope of the line at that point, but using the change in displacement instead of the change in velocity.

In both cases, it is important to make sure that the units of your slope match the units of speed (e.g. m/s). Also, keep in mind that the slope is only an average speed over a specific time interval, so if you want to calculate the speed at a specific instant, you would need to use calculus to find the instantaneous slope at that point.

## 1. How do I determine the speed from a velocity-time graph?

The speed can be determined from a velocity-time graph by calculating the slope of the line. The slope represents the rate of change of velocity, which is equal to the speed. You can find the slope by dividing the change in velocity by the change in time between two points on the graph.

## 2. What units should I use when calculating speed from a velocity-time graph?

The units for speed on a velocity-time graph are typically meters per second (m/s) or kilometers per hour (km/h). However, you can also use any other unit of distance divided by time, such as feet per second or miles per hour, as long as you are consistent throughout your calculations.

## 3. How do I calculate the distance traveled from a velocity-time graph?

The distance traveled can be calculated from a velocity-time graph by finding the area under the curve. The area represents the displacement, which is the total distance traveled. You can use the formula for finding the area of a trapezoid (A = ½(b1+b2)h) or use numerical integration techniques to calculate the area.

## 4. Can I calculate speed from a displacement-time graph?

Yes, you can calculate speed from a displacement-time graph. The speed is equal to the slope of the line on a displacement-time graph, as the slope represents the rate of change of displacement. You can use the same method of finding the slope as you would on a velocity-time graph.

## 5. What is the difference between speed and velocity on a velocity-time graph?

On a velocity-time graph, speed and velocity are represented by the same line. However, the difference between the two is that velocity also includes the direction of motion, whereas speed only represents the magnitude of the motion. This means that two objects can have the same speed but different velocities if they are moving in different directions.

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