1. The problem statement, all variables and given/known data A horizontal force of 2N is just sufficient to prevent a block of mass 1kg from sliding down a rough plane inclined at arcsin 7/25 (=16.3 degrees) to the horizontal. Find the coefficient of friction between the block and the plane and then acceleration with which the block will move when the force is removed. 2. Relevant equations Friction = Coefficient of friction x Resistive force (parallel at a right angle to the slope on which the objects acts on) Force = Mass x Acceleration 3. The attempt at a solution Well what I thought was that the force that the object has should be 2+gsin16.3 which equals 4.75N. This means that the acceleration will be 2.75N when the force of 2N is taken away. However the answer is meant to be 1.97ms^-2... Did I work out the acceleration wrong in the first place? Now attempting to work out the coefficient of friction, I simply did friction over resistive force: gsin16.3/gcos16.3 and that gives me 0.292 but the answer is supposed to be 0.0827... I do not understand what I am doing wrong. If someone can say what I'm doing wrong and lead me into the right direction then thanks! EDIT: Worked out coefficient of friction now but can't work out acceleration.