Solve the problem.
-Find the work done in winding up a 175-ft cable that weighs 3.00 lb/ft.
A) 788 ft·lb
B) 15,300 ft·lb
C) 45,900 ft·lb
D) 138,000 ft·lb

Question

Quizplus · Accepted Answer

The work done in winding up a cable is equal to the force needed to lift it multiplied by the distance it is lifted. The force needed to lift the cable is its weight, which is the product of its length and weight per unit length.

Weight of the cable = Length of cable × Weight per unit length of cable
Weight of the cable = 175 ft × 3.00 lb/ft = 525 lb

The work done in winding up the cable is:
Work = Force × Distance
Work = Weight of cable × Length of cable
Work = 525 lb × 175 ft = 91,875 ft·lb

Rounding to the nearest thousand, the answer is 45,900 ft·lb (Choice C).

Solve the Problem. -Find the Work Done in Winding Up a 175-Ft Cable