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# Build the Fastest Car in the World...that Goes Roughly 0.1 m/s

Ben Pearson

Visual Scientifics is an affordable system that joins video analysis or probeware with core mechanics and lets you blend physics, technology, engineering, and real-world applications. It enhances your laboratory experiments with engaging content that is aligned with National Science Education Standards and Next Generation Science Standards. Plus, this cutting-edge system is designed to be platform neutral, so it works with the tools you already own and know how to use.

The Visual Scientifics Inclined Plane and Car can be used to explore a variety of fundamental concepts, including static and kinetic friction, dynamic equilibrium, unbalanced forces, and the work-energy theorem. Students can apply Newton’s laws to a car rolling down the incline, predict its final velocity, and quantify the work done by friction. With the included pulley system, students can design a simple machine to pull a car up the ramp or down the ramp to meet specific design criteria.

In this experiment, your students design a car using the Visual Scientifics system and a smartphone. The goal is for students to build a car that achieves a speed of roughly 0.1 m/s down the inclined plane, and then to use their smartphone to calculate the X, Y, and actual incline velocity of the car.

I recommend that your students work in groups of 4 to 5 with each Visual Scientifics setup. I also recommend leading this as an inquiry experiment by first asking your students how they would design a car on the inclined plane to achieve a certain velocity. Encourage free-form discussion and then quantify the variables that can be changed to alter the velocity and acceleration of the car, such as angle of the incline, pulley on the end of the incline with masses on the car or mass hanger, etc. Once your students have an initial design of experiments for different configurations, challenge them to determine how they can measure the velocity of the car using a smartphone.

### Next Generation Science Standards

The Visual Scientifics inclined plane activity is appropriate for high school students and addresses the standards listed below. Additionally, the included instructional manual has details for over 25 standards covered by the activity.

• Energy
Construct an explanation of the proportional relationship pattern between the kinetic energy of an object and its mass and speed. Design, build, and evaluate devices that convert 1 form of energy into another form.
• Forces and motion
Plan and carry out investigations to show the algebraic formation of Newton’s second law of motion in 2 dimensions. Use algebraic equations to predict the objects’ velocities after an interaction if the objects’ masses and velocities are known before the interaction.
• Cross-cutting concepts
• Proportional relationships
• Constructing explanations and designing solutions

Per group

### Teacher preparation and procedure

1. Set up the apparatus as shown in Fig. 1. Out-of-the box setup will take 3 to 5 minutes to prepare each station. After initial setup, you’ll need less setup time because string is sized appropriately.
 Figure 1  Apparatus setup.
1. Release the car with no mass and allow the car to go down the incline freely, making sure nothing blocks its path.
2. Tie a loop in each end of the string.
3. Attach 1 loop to the hook or the rod on the car, attach the other end to a mass hanger, and place the string over the pulley.
4. Place the car at the top of the ramp and allow it to go down the ramp.
5. Add a few masses to the hanger and the car so that the car moves slowly down the ramp.
6. Place the car near the top of the ramp and adjust the incline so that the car just begins to move down the ramp slowly.
7. Repeat step 7 until it takes the car roughly 5 to 7 seconds to go down the ramp.
8. Place the car at the top of the ramp and, using your smartphone, record a video of the car going down the ramp. Your camera’s field of view should look like Fig. 2.
 Figure 2  Camera field of view.
1. Play the recorded video on your smartphone, using the time bar to show the video’s duration. If you do not have a phone video player with this capability, upload the video to YouTube, which has this feature.
2. Begin the video and note the time that the car starts moving. Then note the time at the bottom of the ramp before the car cannot be seen against the back board.
3. In Fig. 3, you can see the start time is 2 seconds and the starting position is by B3; the ending time is 6 seconds and ending position is F2, as shown in Fig. 4.

 Figure 3  Start time and starting position.
 Figure 4  End time and ending position.
1. Since you know the start and ending times, you can determine the X and Y velocity and then calculate the velocity of the car on the incline.
1. In this example the change in time (Δt) was 4 seconds, the displacement in the X direction was 0.29 m, and the displacement in the Y direction was 0.075 m (each marking on the back drop is a 1-cm increment).
2. Therefore Vx = 0.07 m/s and Vy = 0.02 m/s; using V^2 = (Vx)^2 + (Vy)^2 we know that the velocity of the car was approximately
0.075 m/s (roughly 0.1 m/s).

### Conclusion

Concepts covered:

• 2-dimensional velocity
• Conservation of energy
• Basic algebra to calculate velocity in 2 dimensions
• Variation of angle and mass configurations shows varied proportional effects on the velocity of the car

### Extension activities

1. Verify the car’s velocity using a photogate.
2. Calculate what the car’s velocity will be with varying masses on the mass hanger.
3. Graph displacement vs. time and velocity vs. time.
4. Design a video experiment that allows your students to obtain the velocity of the car in 1 step, without obtaining velocity in the X and Y direction.

Answer: Take a top view video of the car instead of the base.