1. The problem statement, all variables and given/known data A sled weighing 60 N is pulled horizontally across snow so that the coefficient of kinetic friction between sled and snow is uk = 0.100. A penguin of 70 N rides on the sled. If the co. static friction between the penguin and the sled is us = 0.700 find the maximum horizontal force that can be exerted on the sled before the penguin begins to slide off. 2. Relevant equations fs = us R, fk = uk R. 3. The attempt at a solution Please see the attached file for the force diagrams. Forward force on the sled = F - fs - fk In the absence of the static friction, penguin will slide backward with this force. But the penguin expereinces a force due to static friction fs. F - fs - fk = fs F = 2 fs + fk = 2 us R1 + uk R2 = 2 us m1g + uk (m1+m2)g = 111 N Book answer is 104 N. Can you check my force diagrams please? Thanks.