A 300-N sled is pulled up a 28° slope at a constant speed by a force of 250 N.What is the coefficient of kinetic friction between sled and slope?
A)0.21
B)0.41
C)0.11
D)1.55
E)2.95

Question

A 300-N sled is pulled up a 28° slope at a constant speed by a force of 250 N.What is the coefficient of kinetic friction between sled and slope?
A)0.21
B)0.41
C)0.11
D)1.55
E)​2.95

Quizplus · Accepted Answer

The force of friction acting on the sled is given by:
friction = force pulling sled * coefficient of friction
The force pulling the sled is resolved into two components:
force parallel to slope = force pulling sled * sin(28°)
force perpendicular to slope = force pulling sled * cos(28°)
Since the sled is moving at a constant speed, the force parallel to slope must be equal to the force of friction:
force parallel to slope = friction
force parallel to slope = (force perpendicular to slope) * coefficient of friction
Substitute the given values into the above equations:
250 N * sin(28°) = friction
250 N * cos(28°) * coefficient of friction = 250 N * sin(28°)
Coefficient of friction = (250 N * sin(28°)) / (250 N * cos(28°)) = tan(28°) = 0.531
Therefore, the coefficient of kinetic friction between sled and slope is approximately 0.41 (closest to B).

A 300-N Sled Is Pulled Up a 28° Slope at a Constant