Question 1670 Deck General

The correct answer is C) 69 lbs. This is because with a tackle system of 12, the mechanical advantage is 12. This means that the weight of 300 lbs is divided by 12, resulting in 25 lbs of pull on the hauling part. However, the question states that we should include 10% of the weight for each sheave in the system for friction. With 6 sheaves, the total friction is 10% x 6 = 60% of the weight, or 180 lbs. Adding this friction force to the 25 lbs of pull gives us the total pull of 69 lbs required to lift the 300 lbs weight. The other answer choices are incorrect because they do not properly account for the friction forces in the tackle system.