Two bicycle tires are set rolling with the same initial speed of 3.70 m / s alon
ID: 2133940 • Letter: T
Question
Two bicycle tires are set rolling with the same initial speed of 3.70m/s along a long, straight road, and the distance each travels before its speed is reduced by half is measured. One tire is inflated to a pressure of 40 psiand goes a distance of 17.5m ; the other is at105 psi and goes a distance of 94.0m . Assume that the net horizontal force is due to rolling friction only and take the free-fall acceleration to be g = 9.80m/s2
A)What is the coefficient of rolling friction
?r for the tire under low pressure?
?
B)What is the coefficient of rolling friction for the second tire (the one inflated to 105)?
?
?r
Explanation / Answer
Friction coefficient ? = F(rf)/F(normal) = ma/mg = a/g
s = (v0^2-v1^2)/(2a) ==> a = (v0^2-v1^2)/(2s)
A. At 40 psi, ? = (3.7^2-1.85^2)/(2*17.5*9.8) = 0.02993
B. At 105 psi, ? = (3.7^2-1.85^2)/(2*105*9.8) = 0.004989