Speed

Speed

Middle School

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Learning Objectives

Key Vocabulary

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Speed

The rate an object moves, measuring distance traveled over a specific amount of time.

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Average Speed

The total distance an object travels divided by the total time it takes to travel that distance.

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Instantaneous Speed

The exact speed of a moving object at a particular moment in time, which can change frequently.

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Distance

The total length of the path traveled between a starting and ending position for an object.

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What is Speed?

• Speed is the measure of how fast or slow an object is moving.

• ​It is the distance an object travels in a specific amount of time.

• A fast softball can have a speed of 120 kilometers per hour (km/h).

• The standard unit for speed is meters per second (m/s).

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Multiple Choice

What is the primary definition of speed in physics?

• The distance traveled in a given amount of time.

• The direction of an object's motion.

• How much an object has accelerated.

• The location of an object at a specific time.

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Average vs. Instantaneous Speed

Average Speed

• ​This is the overall speed of an object over the entire duration of a trip.

• ​​It is calculated by dividing the total distance traveled by the total time it took.

• ​It provides a single value that represents the entire journey, evening out speed variations.

Instantaneous Speed

• ​This is the speed of an object at a single, specific moment in time.

• ​​When you look at a car's speedometer, you are seeing your instantaneous speed.

• ​This measurement can change from one moment to the next due to various factors.

Multiple Choice

A car's speedometer shows that it is traveling at 65 miles per hour. What does this reading represent?

• The car's instantaneous speed.

• The car's average speed for the trip.

• The total distance the car has traveled.

• The time remaining for the trip.

The Speed Formula Triangle

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Finding Speed

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Finding Distance

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Finding Time

Multiple Choice

To figure out how far a car will travel at an average speed of 60 km/h for 5 hours, which formula should you use?

• Distance = Speed × Time

• Speed = Distance / Time

• Time = Distance / Speed

• Distance = Time / Speed

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Common Misconceptions

Misconception	Correction
Average speed is the average of your different speeds.	Average speed is the total distance divided by the total time.
Stopping for a break doesn't affect your average speed.	Stopping increases total time, which lowers your average speed.
Speed and velocity are the exact same thing.	Speed is how fast you go; velocity includes direction.

Multiple Choice

A bus travels 20 km in 30 minutes. What is the average speed of the bus in kilometers per hour?

• 40 km/h

• 20 km/h

• 30 km/h

• 60 km/h

Multiple Choice

If a truck is traveling at an average speed of 50 mph on a long trip, why might its instantaneous speed be 0 mph at some point?

• Because the truck may have stopped for a traffic light or a break.

• Because the truck's engine ran out of fuel.

• Because average speed and instantaneous speed are always equal.

• Because the total distance traveled was zero.

Multiple Choice

Terri rode her bike a total round-trip distance of 6 km. The entire trip took her 15 minutes (0.25 hours). What was her average speed for the whole journey?

• 24 km/h

• 12 km/h

• 6 km/h

• 0.4 km/h

Multiple Choice

A train travels for 2 hours at 80 km/h and then for 3 hours at 60 km/h. What is the train's average speed for the entire 5-hour journey?

• 68 km/h

• 70 km/h

• 72 km/h

• 75 km/h

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Summary

Poll

On a scale of 1-4, how confident are you about calculating speed, distance, and time?

• 1

• 2

• 3

• 4