You are using tackle number 3 as shown in illustration D029DG below to lift a weight of 120 lbs. If you include 10 percent of the weight for each sheave for friction, what is the pull on the hauling part required to lift the weight?

Correct Answer: Option D — 52 lbs.

Tackle 3 is a luff tackle (3 parts). With 3 sheaves, the formula P = W(1 + 0.1n) / N applies: P = 120(1 + 0.3) / 3 = 120(1.3) / 3 = 156 / 3 = 52 lbs. This calculation incorporates the required 10 percent friction allowance per sheave for the specified tackle configuration.