Magnetic Braking
Kaden Leung
Stratford Hall
Floor Location : J 200 N

The purpose of this project was to find out how the circumference of a magnetic wheel affects the braking time. In this experiment, a motor with a magnetic wheel will be started by a battery. Then, the battery will be removed and they I will measure how long it takes for it to stop when a magnet is held near it.

My hypothesis was: If the circumference of the magnetic wheel of a motor is smaller, than the wheel will break quicker as measured by time. The reason I thought this was because the magnetic wheel with the smallest circumference will have the smallest radius. Since the magnets of this magnetic wheel are the closest to the rotational point , they will travel less of a distance for less of a speed. Therefore, if the magnets are travelling at a lower speed compared to the larger magnetic wheels, they will not be able to resist the force of the. The reason I came up with this experiment is the Japanese trains. They use magnets to reduce the friction created so it can move faster and they use magnets to break it.

My independent variable is the circumference of the wheel. I did 25.12 cm Circumference (8 cm Diameter), 31.4 cm Circumference (10 cm Diameter) and 18.84 cm Circumference (6 cm Diameter). My dependent variable is the time of braking as measured by time.

Here is a simple version of my method: Take a motor and put it on clay (x3) so they are 4 cm of the ground. Attach cardboard circles with a radius 3, 4 and 5 cm for the three motors. Super glue 12 magnets on each wheel at the edges every 30 degrees. Collect the test leds and alligator clips and attach the motor of the 4 cm radius circle to the digital multimeter. Add the battery like so it is touching both test leds and alligator clips.

After about 20 seconds, remove the battery, start the timer and hold the remaining 14 magnets near it on its repelling side. Stop the timer when it stops.
Record the same for all the replicates and conditions.

Based on the data retrieved from this experiment, when the circumference of the magnetic wheel is at an optimal amount (around 25.12 cm), than the wheel will break quicker as measured by time. The largest wheel broke the fastest. I think this happened because the larger one is harder to rotate and the smaller one can’t resist the force of the magnet.

Some human errors were the placement of the wheel on the axle. The angle is not perfect and so as the centering.

Next time I would use a less flexible material for the cardboard wheel so it will not be warped as easily. In addition, it might be possible to use a line graph to how the decrease of speed over time.