[SOLVED] Finding a Vertical Force given friction and a horizontal force 1. The problem statement, all variables and given/known data Problem: A box with a weight of 50 N rests on a horizontal surface. A person pulls horizontally on it with a force of 10 N and it does not move. To start it moving, a second person pulls vertically upward on the box. If mu(s) =0.4 (coefficient of static friction) what is the smallest vertical force for which the box moves? (answer: 25 N) 2. Relevant equations I think I might use F(s)= mu(s)*normal force because if (mu*n) > F(s) then the object will move (?) but then im not really sure what to do with the 10N 3. The attempt at a solution My original thoughts would be =0.4*50N will give you 20N for the force of friction but that does not give me a vertical force If I were to just think of the vertical force as the normal force then it would just be 50N..? I'm confused, any help is greatly appreciated, thanks!