A sled weighing 54.0 N is pulled horizontally across snow so that the coefficient of kinetic friction between sled and snow is 0.100. A penguin weighing 71.0 N rides on the sled, as in Fig. P4.76. If the coefficient of static friction between penguin and sled is 0.700, find the maximum horizontal force that can be exerted on the sled before the penguin begins to slide off. I figured the friction on the sled with Fk = .1(71 N + 54 N) = 12.5 N Static friction on the penguin is Fs <= .7(71 N) <= 49.7 So I figured that that the point where the penguin is just about to slip off is where the pulling force minus the kinetic friction equals the static friction of the penguin. So I did F - fk = fs F = fs + fk = 62.2 This isn't right however... Any help would be appreciated..