Free Body Diagram - General Physics - Solved Past Paper, Exams of Physics

Download Free Body Diagram - General Physics - Solved Past Paper and more Exams Physics in PDF only on Docsity! 2. (25 pts) An object with mass m is placed on a rough surface. In order to determine the coefficient of static friction (µs), the incline of the surface is slowly increased to angle θ at which the object just barely starts to slide (at this angle, static friction has reached its greatest value). Determine the coefficient of static friction (assume that m and θ are “given” values). m θ N mg fs θ First, make a free-body diagram of the box, as shown above. Then, since we know that at angle θ the box just barely starts to move, the net force on it is still zero. So use Newton’s 2nd Law to sum the forces and set them equal to zero. Fy = N − mg cos θ = 0 Fx = fs − mg sin θ = 0 Of course, we need to know fs before we can solve for µs. So solve the y component for N , and calculate the frictional force: N = mg cos θ fs = µsN = µsmg cos θ Now substitute this into the x component equation, giving µsmg cos θ − mg sin θ = 0 Solving for µs gives µs = sin θ cos θ = tan θ