This is a remake of my Acceleration Lab Apparatus. I was never fully satisfied with it. When I saw this cool CD Spinning Top I knew I could improve my apparatus by grabbing the screw together bits.
I've made two versions. One version requires a CD for the disk while the other has the same printed disk I used previously. The CD version requires less than 5 g of plastic to make. I made a whole lab set in one 2 hour run. Much more efficient.
Both versions simply screw together. This version requires a lot less prost printing work than my first version. I have successfully printed in both PETG and in PLA.
For the rails we used electrical conduit from Lowes or two Pasco tracks on their sides.The rails are held in position using bricks. It is important to note that if the incline is too steep the apparatus will slide rather than roll resulting in bad data. I suppose the data are not bad per se, but they would not reflect uniform acceleration. This can be fixed by coating the cones in Plastidip. The increased friction removes all sliding even for very steep inclines.
Check out this blog post for a little more detail on the lab.
Overview and Background
This activity is based on the Paradigm Lab for the Accelerated Motion unit in the Modeling Physics curriculum. The basic idea is to have the students derive the basic equations for motion that in a traditional physics class the students would simply be provided with.
Research shows that when students build knowledge for themselves they are much more likely to retain that knowledge and will be able to build on that knowledge.
- Students will create graphical models of accelerated motion
- Students will create a mathematical model for accelerated motion
High school physics students
- NGSS Scientific and Engineering Practices
- Developing and using models
- Analyzing and interpreting data
- Using mathematical and computational thinking
- NGSS Crosscutting Concepts
- Patterns - Analyzing data to determine rates of change. In this case, the constant rate of change in velocity and the varying rate of change in position.
- Scale, proportion, and quantity - A small acceleration can result in very large velocities given enough time.
- NGSS Core Idea PS2.A: Forces and Motion
Lesson Plan and Activity
- Show the Acceleration Apparatus and ask students to describe its motion and how it is different from the buggy cars (battery powered cars that move at a constant velocity, used in the last unit)
- Students collect data by marking the position of the disk every second as it rolls down the rails. Just use a dry erase marker on the conduit.
- Students create a position vs. time graph and use the regression functions in their calculators to find an equation that explains the data. If they were careful in their data collection a quadratic equation should fit very nicely to the data.
- Transform the data to velocity vs. time and graph. Students can borrow the idea of a secant line from their math class to accomplish this. The graph should be linear. Find the equation of the line.
- Students whiteboard and share results with the class
- Through Socratic dialog help students determine what the variables and the coefficients in both the equations derived from the position and velocity data. (See example student data below)
- Lab takes one class period
- Whiteboarding and discussion take 1 - 2 class periods
- For each lab group you will need:
- 2 Lengths of electrical conduit
- Bricks to hold the conduit
- 3D Printed Acceleration Lab Apparatus
- Dry erase markers
- Metronome or metronome app, set to 60 beats/minute
- Students should have already developed the Constant Motion Model
Sample Position Time Data
Position Time graph with Quadratic Regression
Velocity data calculated from Position - Time data
Velocity vs. Time graph with Linear Regression
Example whiteboard from student group