A tractor drags a 100 lb. concrete block 5 ft. in 2 seconds. What is the power output of the tractor? 100 ft-lbs. per second 250 ft-lbs. per second 500 ft-lbs. per second 1,000 ft-lbs. per second

250 [lb-ft/s]

Explanation:

To find power we must first find work, which is defined as the product of force by distance.

W = F*d

where:

F = force = 100[lb]

d = distance = 5 [ft]

w = 100 * 5 = 500 [lb-ft]

Now we can calculate the power which is defined as the relationship between work and time.

P = w / t

where:

w = work [lb-ft]

t = time = 2 [s]

P = 500 / 2

P = 250 [lb-ft/s]