ME 211
Problem Set #7 Friction
Winter 2026
One per page!
1) Determine whether the block shown is in equilibrium and find the magnitude and direction of
the friction force when 𝜃=35° _and P = 200 N.
2) Knowing that 𝜃 = 45 𝑑𝑒𝑔𝑟𝑒𝑒𝑠, determine the range of values for P for which equilibrium of
the block is maintained.
ME 211
Problem Set #7 Friction
Winter 2026
3) The ladder is leaning against a wall. The coefficient of friction 𝜇𝑆 is the same at both
points A and B. What is the smallest value of 𝜇𝑆 that allows the ladder to stay in
equilibrium in its current position?
4) Wire is being drawn at a constant rate from a spool by applying a vertical force P to the
wire as shown. The spool and the wire wrapped on the spool have a combined weight of
20 lb. Knowing that the coefficients of friction at both A and B are ms = 0.40 and mk =
0.30, determine the required magnitude of the force P.
ME 211
Problem Set #7 Friction
Winter 2026
5) The plate is attached to collars at A and D that can slide along the vertical rod. If 𝜇𝑆 =
0.40 between both collars and the rod, determine whether the plate is in equilibrium in
the position shown if the vertical force P is (a) P = 0 and (b) P = 20 lb.
6) A 500-N concrete block is to be lifted by the pair of tongs shown. Determine the smallest
allowable value of the coefficient of static friction between the block and the tongs at F
and G.