1. The problem statement, all variables and given/known data The question is attached! 2. Relevant equations mgsintheta = downward force on incline 3. The attempt at a solution I was thinking that this has something to do with the downward force on the incline and making sure that the car doesn't slide down the incline. Changing the mass or curve speed limits may cause the car to slide down the incline but I'm not sure how this makes sense mathematically. And so, I'm trying to understand the mathematical explanation. My answer key says the answer is C.