Question

A 50kg sled is pulled by a rope at an angle of 30 degrees above the horizontal with a force of 35 N. This force is just sufficient to keep the sled moving t a constant speed . What is the coefficient of sliding friction for the sled-snow surface?

Answer 1

Let's write the Second Newton's law for the sled which is moving with a constant speed:
F cos(α) =μ mg;
μ = F cos(α) / mg =35 cos(30) / (50*10) = 0.06