Speed Velocity Momentum Acceleration MatchCard
Objective: Define speed, velocity, momentum, and acceleration.
Provides the definition, formula, examples and demonstration activities for speed, velocity, momentum, and acceleration.
Projects: Toy car for demonstrations. Describe an amusement park ride you would invent using these terms.
Download and Use the Speed Velocity Momentum Acceleration MatchCard
This is MatchCard #6 of the Force and Motion Unit Study. You can find more information on MatchCard Science below.
Definitions and Concepts
This is the easiest for students to grasp. Ask them what they think speed is?
Definition: Speed is the amount of distance in a given time.
Use a toy car to visualize the concept of speed. If you went 25 miles in one hour, what is your speed? What if you went 150 miles in 2 hours?
In physics, speed is often measured in meters per second. When we travel, we often use miles per hour.
Formula: Rate equals distance divided by time
Rate = Distance/Time
Examples of speed:
- 50 mph
- 1,000,000,000 miles per second
- 10 meters per second
What objects might travel the speeds listed above?
Ask what velocity is. How does it compare to speed?
Use your toy car to visualize this example.
Imagine you were traveling to another city at 50 miles per hour. You traveled for one hour. Then you realized you forgot something. The car is turned around, and you go 50 mph for 30 minutes.
Your speed was 50 mph. However, you only traveled 25 miles in one and a half hours.
That is a velocity of 16 mph. Not much progress for someone going 50 mph, is it?
Velocity is often used with airplane travel. In addition to changing directions, air planes also travel up and down. The velocity, however, is speed in a given direction from the beginning to the end of the trip.
Velocity is written as speed in a given direction, and usually the direction is stated.
- North at 45 mph
- Southeast at 350 mph
Ask: What would do more damage? A large truck going 25 mph that hits a building, or a small car?
Momentum is the scientific concept that multiples mass with speed.
Momentum is defined as the power of a moving object to keep moving. In this example the heavier truck had more power to keep moving, so it caused more damage.
Mass X Velocity
In our common language we often talk about "momentum" and "the snow ball effect." This might be a good time to review what the snow ball effect is. The snow ball picks up mass (gets larger) and velocity (speed going downhill) with time. Therefore, it gains momentum.
Popular ideas and trends often are said to "gain momentum" even if there is no scientific object. Can you discuss examples?
Ask what acceleration is. Can you give common examples?
The definition of acceleration is the change in speed over time.
Using your toy car, demonstrate this example:
- Your car is stationary when you first get in.
- Then it begins moving 5 mph for 2 seconds.
- Then it goes 10 mph for 2 seconds.
- Then it goes 15 mph for 2 seconds.
The car accelerated from 0 mph to 15 mph in 6 seconds.
Discuss the feeling of acceleration when a car is merging onto a highway. You can also refer to acceleration on a bike or jet.
Scientists usually measure acceleration in meters per second per second. In the example above, the original time listed was 15 mph. That would actually be 1600 meters (one mile) in 3600 seconds (one hour) per second.
That would be .444 meters per second per second.
Or, every second the car went .444 meters faster than the second before.
The formula is change in speed divided by time.
Change in Speed/Time elapsed
Deceleration is the negative change in speed over time. Compare the sensations of accelerating and decelerating.
Brainstorm a list of things that accelerate. Add to the list over the weeks of your Force and Motion Unit Study.
Go for a Spin
Using a car or other mode of transportation, consider how speed, velocity, momentum, and acceleration are related.
Think of why light weight cars are raced and not 18 wheelers.
How do speed, velocity, momentum and acceleration apply to amusement park rides? Describe a new amusement ride you would like to invent, and use these terms in your description.