20. Plate AB has a random weight W ~ N(5, 0.01²) lb due to manufacturing imprecision. Determine the distribution of normal forces at A and B if the inclined wall is smooth and the static coefficient of friction between the plate and horizontal wall is .

Solution

Solve the equation above, we can obtain

Finally, we have N_A ~ N(4.262, 0.0085²) lb and N_B ~ N(1.476, 0.003²) lb. Ans.