1. The problem statement, all variables and given/known data What force have to be applied to stop an polymer object with mass 5 gram and velocity 0.1 mm/s to stop in 0.2 mm? The polymer object touches a human skin at one side only, whereby friction Ff has a influence in the stopping process. The object is moving to the left. In contrast to a normal problem, the stopping force is not a opposite one, but a perpendicular force. See image below. _________________________________________ (human skin) ← □ (object moves with directon to the left) ↑ (perpendicular force - to the object and the human skin - to stop the object) 2. Relevant equations F = ma 3. The attempt at a solution To my knowledge, the formula F = ma is used to calculate the value of a opposite force to stop a object. Which formula do you use in case of a perpendicular force with respect to friction? Many thanks!