Friction Theory
The refrigerator has a weight of 180 lb and rests on a tile floor for which µ = 0.25.
a. If the man pushes horizontally on the refrigerator in the direction shown,
determine the smallest magnitude of force needed to move it.
b. If the man has a weight of 150 lb, determine the smallest coefficient of friction
between his shoes and the floor so that he does not slip.
A 45 lb ladder 14 ft long rests on a horizontal floor and is supported by a smooth
vertical wall. The ladder is inclined at angle θ as shown and starts to slip when a
person with a weight of 160 lb has climbed halfway up it. Circle yes for one bonus
mark. The coefficient of friction at the floor is 0.42. Assume the weight of the ladder
to be concentrated at its midpoint. Calculate the angle θ.
7 ft
7 ft
θ