Motion Mini Lesson

Calculating Average Speed
By: Mrs. Greco

Multiple Choice

What two measurements are needed to calculate average speed?

• total distance and total time

• mass and time

• volume and mass

• speed and distance

For example

Look at these two cars. They both are going to travel a certain distance.

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Different average speeds

Both cars are going to travel a total distance of 4 miles but they both may not reach the destination at the same time.

Open Ended

What are some reasons why both cars might not reach the destination at the same time?

Different Speeds

One driver may drive slower or faster than the other driver.

Different speeds during journey

The drivers may not drive at the same speed throughout the entire 4 miles. Maybe one went 40 miles per hour for the first two miles then went 60 miles per hour for the last 2 miles.

Calculating Average Speed

To calculate the average speed of an object you need to use the avearge speed formula.

Average Speed Formula

The S stands for Average speed

The D stands for Distance

The T stands for Time

Multiple Choice

What does the S stand for in the average speed formula?

• Average Speed

• Distance

• Time

Multiple Choice

What does the D stand for in the average speed formula?

• Average Speed

• Distance

• Time

Multiple Choice

What does the T stand for in the average speed formula?

• Average Speed

• Distance

• Time

Using the avearge speed formula

To calculate the average speed of an object you need to DIVIDE the distance an object traveled by the time. The distance number goes in the calulator first.

Lets practice calculating average speed

Use a calculator(such as Desmos or Google Calculator) to help you!

Multiple Choice

What is the formula for average speed?

• Average Speed = Total Time \ Total Distance

• Average Speed = Total Distance \Total Time

• Average Speed = Total Time + Total Distance

• Average Speed = Total Distance \times× Total Time

Multiple Choice

On a distance vs. time graph, the steeper the slope _____

• the slower the speed
• the faster the speed
• less acceleration
• greater acceleration

Finding the time

Look at the graph and notice that time numbers are found on the bottom of the graph. The highest time number is 7 seconds.

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Velocity

By Mrs. Greco

Multiple Choice

Cesar drove from Houston to Dallas in 4 hours. Dallas is roughly 250 miles NW of Houston. What was his average speed?

• 1000 mph

• 55 mph

• 62.5 mi/hr NW

• 62.5 mi/hr