Hub Hobby Shop

Newton Car or mouse trap car?

To clear up a misconception: a Newton Car is not a Pinewood Derby car, but it could be a mouse trap car. A Newton Car is a test platform to demonstrate Newton’s 2nd Law of Motion.

What it is . . is Physics. Ouch!

This is commonly a middle school/junior high science project testing the students critical thinking, ability to form a hypothesis, and test to it.


mouse trap


But first a review: Newton had 3 Laws of Physics.

1: An object at rest will stay at rest unless an external force acts upon it.

2: Acceleration is produced when a force acts on a mass. The greater the mass (of the object being accelerated) the greater the amount of force needed (to accelerate the object.)

3: For every reaction there is any equal and opposite reaction.

A digression: Whenever I think of high school science class I recall that we use to say that if its green and wiggles, its biology; if it stinks, its chemistry; and if it doesn’t work, its physics.




Back to the Newton car. Basically you’re making a slingshot: two dowels on opposite ends of the front of a block of wood; one dowel located dead center in the rear. A string attached to the rear dowel, holding a rubber band in the “ready” position until the string is cut.

Cutting the string will cause the rubber band to launch its payload, which can be a 35mm film canister or a pill bottle. Depending on what’s loaded in the bottle will determine how far the car will be propelled in the opposite direction.

They’re not going for distance: they’re testing to see how far differently weighted bottles (i.e. mass) will travel. Also what happens when more than one rubber band is used for propulsion. (post hoc, ergo proctor hoc. . . . couldn’t resist).

Oops! I got ahead of myself: we forgot the wheels.


mouse trap car


For this you could use wheels from a pinewood derby car. Use a 1/8 inch brass tube as a bearing to hold the 3/32 inch axle. Attach the assembly to the bottom of the block of wood using 1/8 inch nylon landing gear straps. To attach the wheels, use 3/32 inch wheel collars on either side of the wheels. The inside collar acts as a standoff; the outside collar keeps the wheel from falling off.

Sketch courtesy of NASA

Latest posts by Hub Hobby (see all)

Leave a Reply