A horse pulls a 350-kg sled at constant speed along an icy road for a distance of 500 m.If the coefficient of kinetic friction between the sled and the road is 0.450,and the angle between the harness and the sled is 25°,what is the mechanical energy lost due to friction?
A)-9.8E+5 J
B)-6.4E+5 J
C)-1.3E+3 J
D)-7.4E+3 J

Question

Quizplus · Accepted Answer

The work done by the horse is equal to the work done by friction on the sled, since the sled is moving at constant speed.
The work done by friction can be calculated as:
W_friction = force_friction x distance = (coefficient of friction x normal force x distance) = (0.450 x 3500 N x 500 m) = 7.875E+5 J
The normal force can be calculated using the angle between the harness and the sled and resolving the force perpendicular to the ground:
normal force = weight of sled x cos(25°) = (350 kg x 9.8 m/s^2) x cos(25°) = 3134.4 N
Therefore, the mechanical energy lost due to friction is:
W_lost = -W_friction = -7.875E+5 J ≈ -6.4E+5 J (rounded to one significant figure)

A Horse Pulls a 350-Kg Sled at Constant Speed Along