If a rubber tire having a weight of 18.0lbs requires a force of 38.0N to keep it in uniform motion on a level highway find the coefficient of kinetic friction.
To find the coefficient of kinetic friction, we need to use the given information about the weight of the tire and the force required to keep it in motion on a level highway.
The force required to keep the tire in uniform motion is the force of friction acting against the tire's motion. This force can be calculated using Newton's second law:
Force of friction = mass × acceleration
In this case, the mass of the tire can be obtained by converting its weight from pounds to kilograms:
mass = weight / acceleration due to gravity
acceleration due to gravity is approximately 9.8 m/s².
So, mass = 18.0 lbs / (9.8 m/s² × 2.205 lbs/kg) = 0.796 kg (rounded to three decimal places).
Now, we can calculate the coefficient of kinetic friction by dividing the force of friction by the normal force. On a level highway, the normal force is equal to the weight of the tire:
coefficient of kinetic friction = force of friction / normal force
normal force = weight = 18.0 lbs × 9.8 m/s² × 2.205 lbs/kg = 156.088 N (rounded to three decimal places).
Therefore, the coefficient of kinetic friction is:
coefficient of kinetic friction = 38.0 N / 156.088 N = 0.243 (rounded to three decimal places).
So, the coefficient of kinetic friction for the rubber tire is approximately 0.243.