us 0.3, find a) the greatest angle A block of wood of mass 150g rests on an inclined pale. If to
which the plane may be tilted without the block slipping. b) the force parallel to plane necessary
to prevent slipping when the angle of the plane with the horizontal is 300. [5 points 1. A box
weighing 5 kg is pulled along a level floor at constant speed by a rope that makes an angle of 300
with the floor. If the force applied on the rope is 10N, what is the coefficient of sliding friction
between the box and floor? [5 points 2.
Solution
2) vertical forces
a) weight
b) component of force
c) nromal reaction
W = N + F sin 30
5*9.8 = N + 10 sin 30
N = 44 N
uN = F cos 30
u*44 = 10 cos 30
u = 0.2
so the coefficient of sliding friction is 0.2