Energy, Power, and Mousetraps

Physics F 2011 Mousetrap Vehicles Yesterday (Monday, October 3rd) was race day for our mousetrap cars.  View the video at the link above.  All in all, it was a really fun experience that taught me a whole lot of different things.  I will answer some questions about this below.

You can also view our documentation written by C. Nolan here.

1.  Why did all the vehicles move differently if they all started with the same amount of stored energy?

Well, I would say that there were two factors that talk about this.  The first is the mass and shape of the vehicle.  A heavier vehicle will be harder to move.  The second idea is the way the energy is transferred from the mousetrap to the car itself.  Our car has the mousetrap pulling a string that unravels by rolling the rear axle, whereas the other team in our class’s vehicle has the power transferred to a ball that is catapulted and pulls the rest of the vehicle forward.

2.  What types of energy were present in your vehicle at different times?

The first type of energy present in my vehicle was potential energy stored in the mousetrap.  This is stored in the spring that is held back when the mousetrap is set.  Once the mousetrap is set off, it creates kinetic energy that is transferred first to the string, and secondly to the rear axle.  The irrelevant energy generated was the heat energy from the friction of the string rubbing against the wheel.  Of course, the goal was to create a low-friction environment, but this is impossible without an extremely controlled outside environment.

3.  Which car was the most powerful?

Of the two cars we raced in F Period, I believe the other car, was more powerful.  The reason for this was that it had a single, very quick snap, compared to our quick, but more spread out snap.  The initial part of the “launch” was the part when our vehicle had the greatest power, because the inertia that it started with caused the wheels to slip at the very first tug by the mouse trap.  After that, the power decreased as the entire mousetrap slowed down as it spun the wheels, until it stopped.

All in all, I’m sad that this project is over, but I’m very satisfied with how it turned out.

The most important things to remember for next time are to use something that is proven, then expand on it. I started this time with ideas like pushing the car directly with the mousetrap and spinning a gear, but the I didn’t begin by trying to address the most important How Might We question: how can we spread out the energy of the mousetrap throughout a longer period of time, rather than having a single, quick snap.  The lack of this knowledge led to very few prototypes of my final model, and a rough model at the end.

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