MESA Day 2013Mousetrap Car
6th-8th Grade - Distance 9th-12th Grade - Accuracy
Objective & Materials Students will build a vehicle solely
powered by a standard mousetrap to travel the longest distance on a specified track (MS) or stop the closest to a specified target (HS).
Materials: 1 standard mousetrap All other materials are legal
NO KITS!
READ RULES AT LEAST TWICE!! Mousetrap is ONLY source of
energy Don’t tamper with mousetrap:
No paint No decoration Alteration allowed ONLY for attaching
mousetrap to chassis Spring may not be altered
READ RULES AT LEAST TWICE!!
FIRST THINGS FIRST:
Let’s review physics! Energy: It’s what moves the car.
Potential: energy stored in a system (mousetrap spring) Elastic & Gravitational
Kinetic: energy of motion Potential Kinetic
Inertia: The resistance an object has to changing its state of motion.
Rotational Inertia: The resistance an object has to changing its state of rotation.
Friction: A force that opposes the direction of motion. Static: caused from two surfaces pressing together. Fluid: caused from liquids or gases. In air, this is
known as drag. Torque: The force required to rotate an object. Power: The rate at which energy is released or
transformed in a system.
The Engine: Spring + Lever Arm
Energy from spring is transferred to car via the lever arm
Lever arm provides torque required to turn axles
Length of lever arm affects power output
Shorter arm = faster outputLonger arm = slower output
Wheels & Axles # of wheels : 3 or 4 Wheel radius
The greater the radius, the greater the torque required to rotate the axle
Wheel grip (traction) Power output must match wheel grip to avoid
spinning Avoid wasting energy
Ratio of wheel-to-axle Larger ratio good for distance, but not necessarily for
accuracy Friction
Reduce friction between wheels and surface Also between axle and chassis
Alignment
Wheels & Axles
The Chassis The body of the car Balsawood, plastic, other lightweight materials Mass
The heavier the car, the greater the friction force with the surface
More force required to actually move the car Long chassis vs. Short chassis Narrow vs Wide Aerodynamics (negligible)
Fast vs Slow
Accuracy: Can be fast or
slow Length of lever
arm Wheel and axle
size Braking
mechanism? quick power
output
Slow: Build a car that will
accelerate slowly over the entire distance that it travels. Less “coasting”.
longer lever arm larger wheel radius slow power output
Fast: Build a car that will
accelerate quickly and “coast” as far as possible
shorter lever arm smaller wheel radius quick power output
Tips for avoiding DQ’s: Research, research, research! Experimentation is the key Set a working timeline READ THE RULES….twice….again!! HAVE FUN!!!: It’s not the end of the
world.
Remind Students: Research, research, research! Experimentation is the key Set a working timeline READ THE RULES….twice….again!! HAVE FUN!!!: It’s not the end of the
world.