Energy, Machines, and Motion
Part Three: Motion
Lesson 19: Motion of a Mousetrap Car
Students use a mousetrap car to investigate its motion. Students measure the speed of the mousetrap car as it travels along a track and identify the forces acting on the mousetrap car.
Focus Question: How does the size of the force affect the motion of an object? How does the duration of the force affect the motion of the object?
3. Lesson Set-up and Management
EALR 2:
Inquiry
Core content: Questioning and Investigating
6-8 INQC Collecting, analyzing, and displaying data are essential aspects of all investigations.
EALR 4:
Physical Science
Core Content: Balanced and Unbalanced Forces
6-8 PS1A Average speed is defined as the distance traveled in a given period of time.
6-8 PS1B Friction is a force that acts to slow or stop the motion of objects.
6-8 PS1C Unbalanced forces will cause changes in the speed or direction of an objects motion.
- Students identify and describe the forces acting on the mousetrap car.
- Students observe and measure the speed of the mousetrap car as it moves.
- Students describe how forces affect the motion of the mousetrap car.
- Students identify energy transformation in the mousetrap car.
- Students compare the motion of the fan car and the motion of the mousetrap car.
3. Lesson Set-Up and Management
Materials:
- Students will construct a mousetrap car. Students can use the diagrams in the student edition to assist them in this construction. Students in the first class will build the mousetrap cars; the cars can be used by subsequent classes.
- Students attach the mousetrap to the car with string. Rubber bands and tape are other options for keeping the mousetrap attached to the vehicle.
- Have a completed mousetrap car for students to use as a model.
- Students will use nylon string to set the trap of the mousetrap to the rear-wheel axle. Make sure the string is long enough. If it is too short it will “kick back”. It is alright for students to observe this. If students experience this, have them replace the nylon string with a longer piece.
- After you are finished with the mousetrap cars, store the pieces in individual baggies for easier use the next time you teach the lesson.
Student Management: Lesson 19.1
- Students will want to engage their mousetrap cars right away, however prior to engaging mousetrap cars, students need to measure the force of their spring. Have students move the trap to different locations they can be just a little bit, half-way and all the way back. What do they notice about the force?
- Students then need to set the trap and allow the trap to engage without having the wheels on the ground.
- Students then predict the motion of the car if it was allowed to be
engaged on the ground. This is a good time to pull out the
misconceptions students may still have about motion.
I predict that when the mouse trap snaps and the car starts to go that the first it will be moving pretty slowly. I think this because in our last lesson we learned that our cars usually start out going a slow speed. But once the car is going down the track it will be going its top speed, because also in our last lesson we learned the car is going its top speed at the end of the track. Finally when it is down at the end of the track I think the mouse trap car will be slowing down more and stopping, because the applied force (string) is no longer applying a force. So now friction is bigger than the applied force which will make it stop. (Sixth Grade Student)
- Students can then “play” with their vehicles. During this “play time” students should focus on the motion of the mousetrap car.
- Students then write a paragraph describing the motion of the
mousetrap car. Consider using the
Observational Organizer to help students write their paragraphs. Below is
an example taken from a middle school student’s notebook:
I noticed that when we tested our mouse trap car that it went its top speed when the trap snapped shut. I also noticed that the car got slower as the car went farther. I was surprised the car did not go very far. Even when we pulled the clamp back really far, the car only moved about 4 feet at the most. I wonder if we used a bigger, stronger mousetrap on the car would it go farther?
- Students will construct their cars at different rates, be prepared for this.
- Lesson 19.2 students will be asked to write their own procedures for tracking the speed of the mousetrap car as it moves along a track. Students will also need to create a data table to record their measurements along with any calculations. Plan adequate time for students to complete this task.
- Have access to an area where students can engage their mousetrap cars without obstacles. Gyms, hallways and common areas work well for students to investigate their vehicles.
Writing Support:
- Consider using a claims and evidence chart for students to describe the motion/speed of the mousetrap car. After students have made several claims and evidence they should draw conclusions based on what they have seen in the motion of the car and in their data.
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Claims: |
Evidence from Data Collected |
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Conclusion drawn from my data:
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- Students are asked to compare the motion of the fan car with the
motion of the mousetrap car. Consider using the Box and T-Chart to
organize how the two vehicles are the same and how they are different.
- After students have compared the two vehicles they can use the
Writing Comparison writing frame to write about the similarities and
differences. Below is an example from a middle school student:
The mousetrap and fan car and the roller coaster car are the same because they were all able to travel along a track using different forces. In each case the vehicles had friction on the tires and the axles. All three cars were able to move using an energy source other than a human. The cars were different because the fan car and mousetrap car each needed an applied force to make them start moving, but the rollercoaster car used gravity to start its motion. The speed was also different. The fan car speed up as it traveled, the mousetrap car got slower, the roller coaster car however changed from faster to slower on different parts of the track.
- Consider giving students a paste-in of the mousetrap car. Have
them label energy transformations that are taking place as the vehicle
is engaged.
Reading Support:
- Two reading selections follow Lesson 19, the first reading “Rocket Science 101” provides students with background information about the amount of force needed to propel a rocket into space.
- The second reading, “Medieval Warfare in Modern Times,” provides students with real world examples of how spring forces have been used throughout history.
Math Support:
- Students practice their skills of calculating speed at different portions of a track. Review the equations for calculating speed.
- Students need to develop a data table to collect the time traveled along a track. Support students who still struggle with this skill.
Last updated 09/09/2009