Pressure to Find Weight of Car?

Question

Mike has set the gauge pressure of the tires on his car to 36.0 psi (lb/in^2). He draws chalk lines around the edges of the tires where they touch the driveway surface to measure the area of contact between the tires and the ground. Each front tire has a contact area of 24.0 in^2 and each rear tire has a contact area of 20.0 in^2. What is the weight (in lb) of the car?

Answer 1

P = F \ a

As P is pressure

F is force ( due to gravity ) which is weight

a is area ( of the 4 tires )

a = 48 + 40 = 88 in^2

So

F ( weight ) = P a = 36*88 =3168 lb

Answer 2

3168 lbs.  Take your pressure in each tire and multiply it by the area to give you the weight of each tire, then add all the weights.