Mountain Bike Tire Pressure
Pressure question (physics)?
a person who weighs 625 N is riding a 98N mountain bike. uppose the entire weight of the rider and bike is supported equally by the two tires. If the guage pressure in each tire is 7.60 X 10^5 Pa, what is the area of contact etween each tire?
—> i’m using the equation P=F/A
**first i added the forces (weight of rider+weight of bike=723…. then i devided it by two… since i’m looking for the area of each INDAVIDUAL tire. when i did taht… i got that the force exerted by each tire= 361.5N
**next… since i am given pressure (7.60 X 10^5 Pa) i just plugged in all my infromation into the equation: P=F/A —>> 7.60 X 10^5 Pa = 361.5/A —>> A= 4.7 X 10 ^ -4
i don’t understand why my answer is negative
soooo if you could please tell me what you did to get your answer i would honestly appreciate it. thankks for your time and patience! 
Your method and answer are both absolutely correct. You have not got a negative answer.
4.7*10^-4 = 4.7/10^4 m^2 = 4.7 cm^2
It is a very small number because the pressure in the tyres/tires is very high.
Hope this helps you.
How to Inspect Your Mountain Bike Before Riding Video
