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Today we will figure out how to measure the weight of your car and then go out and measure it. In order to do this we first must know the weight of your car to compare our result from experiment.

The main idea to use is what is pressure? In our case it is the tire pressure. From the lectures we have seen that the definition of pressure is:

Pressure = Force/Area

This means that pressure is a measure of how the applied force is distributed over an area. In our case the force is the gravitational force of the earth on the car => the cars weight. This weight is distributed over the ground by the surface area of the tires touching the ground. With this information let's see if we can come up with how to measure the weight of your car.

1). If the tire pressure is low does the tire cover more ground or less? When the tire pressure is high does the tire cover more or less ground? What does this tell you? Is there a relationship between pressure and area?

2). Using what you have learned from part 1 and knowing that the force you want is the weight of your car and that pressure equals force divided by area, try to figure out a way to measure the weight of your car.

3). One thing we know we have to measure is the tire pressure. Using the pressure gauge given measure one tires pressure. You also have probably figured that you need to measure the area the tire makes with the ground. How might you do this? Now measure the area.

4). Using parts 2 and 3 determine the weight of you car and compare it to the known weight. Why might the two values disagree?