an 85kg concrete block rests on a flat surface with coefficient of static friction=0.42. find the maximum force that can pull on the block with, angle of 38 degrees above the horizontal without moving the block?
vertical force = m g - F sin 38
horizontal force
=.42*vertical force - F cos 38
when the horizontal force is zero, it is about to accelerate
so when
F cos 38 = .42 (85*9.81-F sin 38)
solve for F