1. The problem statement, all variables and given/known data A cart of mass mA = 5.7 kg is pushed forward by a horizontal force F. A block of mass mB = 0.76 kg is in turn pushed forward by the cart as show on the picture: (The picture shows 9.8m/s^2 pointing down, Force coming from left to right point at the cart which weighs 5.7 kg which then has a block (not of the same size, smaller) weighing 0.76 kg positioned in the middle of its side. They have a friction constant of 0.63) If the cart and the block accelerate forward fast enough, the friction force between the block and the cart would keep the block suspended above the floor without falling down. Given g = 9.8 m/s2 and the static friction coefficient μs = 0.63 between the block and the cart; the floor is horizontal and there is no friction between the cart and the floor. Calculate the minimal force F on the cart that would keep the block from falling down. Answer in units of N. 2. Relevant equations Netforce = ma 3. The attempt at a solution I have two free body diagrams but I think my normal force is incorrect. On the 5.7 cart, I have Force point from left to right, P21 point from right to left (the force from the .76 block on the 5.7 block), friction point up and w pointing down. I have normal force point up but I feel that it might be incorrect because friction is also present in that direction. For my second, I have P12 from left to right (force from 5.7 block to .76 block), friction pointing up and w pointing down. With this normal force also pointing up but I have the same issue. So for the 5.7 block, I have xnetforce = F - P21 = 5.7ax. For the ynetforce = n1+f1-w1=5.7ay. For .76, xnetforce = P12=.76ax. ynetforce = n2+f2-w2=.76ay. Is my normal force wrong or am I totally missing how I can solve this?