Friction and Newton’s First Law Questions

Question

Please help.

In the horizontal starting area of a four-person bobsled race, the four athletes, with a combined mass including outfits of 295 kg, exert a minimum horizontal force of 41.0 N [F] to get the 315 kg sled to begin moving. After the sled has travelled for almost 15.0 m, all four people jump into the sled, and the sled then experiences a kinetic friction of magnitude 66.0 N. Determine the coefficient of kinetic friction.

Answer 1

Here Kinetic Friction, F_frk = 66.0N.

The associated normal force acting on the sled surface N balnces the weight of the sled and that of 4 persons.

N= (315+295)kg * g = 610*10 = 6100.0 N [ Using g= 10 m/s²]

efficient of kinetic friction = F_frk/ N = 0.011