1. The problem statement, all variables and given/known data Why is it important that the string be parallel to the plane? Use Diagrams to illustrate. 2. Relevant equations F = ma 3. The attempt at a solution I believe that if the string is parallel to the plane it requires more force than if it were inclined because pulling up on the cart reduces the FN. This makes the cart less heavy, reducing the friction. I have included an attachment of my diagram that I made.