# Can Car

Topics: Force, Classical mechanics, Energy Pages: 2 (734 words) Published: April 29, 2013
CAN CAR Essay Keaton Mertz
Simms-D

The goal of the can car lab was to create a rubber band-powered car that demonstrates Newton’s laws, and conservation of energy. The advantages of having a heavy rolling can is that I would have a lot of rotational energy and momentum, the disadvantage is the car has more static inertia. If the car has more static inertia, then it will be harder for the can to roll backwards at the end of its run. The factors affecting the can’s net force (once the rubber band is unwound, but when the car still has momentum) are, force of gravity, normal force, KE, rubbing friction (into heat), the re-winding of the rubber band, wind, and air resistance. The force of gravity and support force cancel out, the wind almost cancels the air resistance against the can, and the KE is a greater force at this moment than the air resistance, re-winding (PEe), and the friction. At this moment the car is able to go forward. The PEe rewinding gets greater as the can moves due to the amount of force need to spin the rubber band increasing. Force car pushes on road, for road on car and the Force popsicle stick in on to the can lid, force can lid pushes out on the popsicle stick. The energy of the can car is conserved because the PEe i (initial kinetic energy equals zero) is equal to the combination of the PEe f and the KEf which goes into dissipative forces, thermal energy through friction, or the energy is wasted through slippage. In my can car a lot of force was dissipated, to the point that PEi was greater than Ef. The can starts moving because once the rubber band is completely twisted, the wound rubber band tries to unwind. It should be easier for the rubber band to unwind by rotating the can than rotating the weights. Cans do not roll back and forth, because (at least in a my big can) the rubber band has the least amount of tension when it is barely wound (meaning a small force in PE=Fd), due to not having very much PE the can can not overcome...