Final answer:
The total work done by the farmer when lifting a dozen 14.4 lb sacks of grain 2.1 ft above the ground is 362.88 ft-lbs. This is found by multiplying the total weight of the sacks by the height they've been lifted.
Step-by-step explanation:
The total work done is calculated by multiplying the force applied by the displacement in the direction of the force. For lifting objects, the force is equal to the weight of the objects, and the displacement is the height they've been lifted. The weight of each sack is 14.4 lbs, and since there are a dozen, the total weight lifted is 14.4 lbs × 12. The total displacement is 2.1 ft vertically upwards. Thus, the total work done (ft-lbs) is the product of the total weight and the displacement.
Calculating, we have: Work (W) = Force (F) × Distance (d), where F = 14.4 lbs × 12 sacks and d = 2.1 ft. Therefore, W = (14.4 lbs × 12) × 2.1 ft = 172.8 lbs × 2.1 ft = 362.88 ft-lbs. This is the answer to the question posed by the student regarding the total work done.