Essential University Physics: Volume 1 (4th Edition)

We find: a) $W_{app} = W(1 - \frac{P_w}{P_c}) = 25(1-\frac{1}{19.3})=23.7\ N$ b) $\frac{P_c}{P_w} = (.75)(19.3) + (10.5)(.25) = 17.1$ $W_{app} = W(1 - \frac{P_w}{P_c}) = 25(1-\frac{1}{17.1})=23.5\ N$