Rolling Friction?. Two bicycle tires are set rolling with the same initial speed of 3.50 m/s on a long, straight road, and the distance each travels before its speed is reduced by half measured. One tire is inflated to a pressure of 40 psi and goes 18.1 m; the other is at 105 psi and goes 92.9 m. What is the coefficient of rolling friction ???r for each? Assume that the net horizontal force is due to rolling friction only.

Solution 69P Step 1 of 4: The coefficient of rolling friction( )rwhich is the horizontal force needed for constant speed on a flat surface divided by the upward normal force exerted by the surface. F r That is, coefficient of rolling friction, r = Fnormal Using F = ma and F = mg r normal ma r mg = a …………...1 r g Step 2 of 4: Using kinematics equation, u v = 2as Solving for acceleration, u v a = 2s ………..2 Using equation 2 in 1, = u v ………………...3 r 2gs Where u and v are the initial and final velocities, s is the distance and g is acceleration due to gravity.