Finding the Center of Mass for a Pinewood Derby Car

[bart Sherer]

I am trying to determine the center of mass of a pinewood derby car. Any suggestions on how this can be done?

 

[mgb_phys]

On paper, my measuring the shape and mass of each component - calculating their individual CofG then calculating the overall value.
Or just balance the finished car on a knife edge.

 

[bart Sherer]

Thanks. There is also a lot of discussion as to where the weight in the car shoud be placed. I assume the weight should be placed as low as possible and as far back on the vehicle as possible. Your input is appreciated.

 

[Integral]

Hang the car from the middle of a string, the hanging (free) end of the string will pass through the cm. Do this from 2 different points, the intersection is your cm.

 

[Andy Resnick]

To find the center of mass, you actually need *3* different 'hangings' because the car is 3-dimensional. Two will identify the line that passes through the center of mass, the third will reduce it to a point.

In any case, IIRC, the number 1 design consideration is the wheel friction. The wheels must spin freely and be lubricated. Then, the weight and aerodynamics come into play.