🚀 go-pugleaf

>We will be presented with a car on a concrete floor in an auto shop and 
>given a maximum of 10min to determine the mass of the car in Kg.
>The car may be loaded unevenly (i.e., the weight of the car may not be 
>equally distributed on the 4 tires).  The tires may or may not be of the 
>same type (tread design, diameter, circumference, width etc.)
>The car will remain locked during the exercise.  We may not lift the car 
>in any manner, manually or mechanically.  We may not use any balances to 
>measure the mass or the weight of the car directly.
>We may measure any external features of the car (such as length, width, 
>height, tire pressure, tire dimensions, etc.).  (We must bring our own 
>measuring devices.)
>Scoring is based on how close to the actual mass of the car as determined 
>by the judges.  Ties will be determined by the shortest time taken to 
>complete the task.

I wonder how well this would work:  Around each tire, build a dam.  It 
encloses a known area and has a rim of known height.  Fill the dam with 
water to the top of the rim.  The less water it takes to fill the dam, 
the larger is the area of the tire bearing on the floor.  From the amount 
of water taken to fill the dam, use a table prepared in advance to 
determine each tire footprint area.  Multiply this by each tire's 
pressure to get the force on each tire.  The sum of these should be the 
weight of the car.  Divide by 32.2 feet per second per second or whatever 
it is you use up there *8) to get the mass.  
               Can't think of any other way right now.

                                   M Kinsler