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 N [fwd] to get the 315-kg sled to begin moving. After the sled has travelled for almost 15 m, all four people jump into the sled, and the sled then experiences a kinetic friction of magnitude 66 N. Determine the coefficient of (a) static friction and (b) kinetic friction. [3]