a box of 5kg lies on a ramp of inclination 30degrees. Calculate the maximum static friction force needed to keep the box stationary
the normal force is...5 g cos(30º)
the force along the ramp is
... 5 g sin(30º)
5 g sin(30º) = μ 5 g cos(30º)
sin(30º) / cos(30º) = tan(30º) = μ