This being the total work done, the work per man = nearly 600.3 foot-tons.
A hill-coolie weighing 150 lbs. goes 30 miles with an ascent of 5,500 feet in three days, carrying 80 lbs. in weight. What is the work per day? (Parkes.)
Work of the ascent = (150 + 80) × 5,500 ∕ 2,240 = 564·7 foot-tons.
Work of 30 miles walk = 230 × 30 × 5,280 ∕ (20 × 2,240) = 813·2 foot-tons.
Total work = 564·7 + 813·2 = 1,377·9.
Total work per day = 1,377·9 ∕ 3 = 459·3 foot-tons.
Suppose a man weighing 150 lbs. in his clothes, carries a load of bricks weighing 35 lbs. up a perpendicular ladder 30 feet high, 100 times daily, what amount of work does he do; and what will it equal in miles walked upon a flat road at the rate of 3 miles an hour?
- (150 + 35) × 30 × 100 ∕ 2,240 = 247·8 foot-tons
- (185 × D) ∕ (20 × 2,240) = 247·8.
- Therefore D = 60,056 feet>
- = about 11·4 miles.
Suppose a man strikes 12,000 strokes in 5 hours with a 14-lb. hammer, raising it at each stroke 4 feet, how much work does he do? Compare this with a walk of 15 miles on a level ground at 3 miles an hour, the weight of the man and what he carries being 180 lbs.
- (a) 12,000 × 14 × 4 = 672,000 foot-lbs. of work
- = 300 foot-tons.
- (b) (180 × 15 × 5,280) ∕ (20 × 2,240) = 318·2 foot-tons.