Solve the problem.
-A construction crane lifts a bucket of sand originally weighing 135 lb at a constant rate. Sand is lost from the bucket at a constant rate of 0.5 lb/ft. How much work is done in lifting the sand 70 ft? (Neglect the weight of
The bucket.)
A) 7000 ft · lb
B) 8225 ft · lb
C) 9450 ft · lb
D) 10,675 ft · lb

Question

Quizplus · Accepted Answer

The amount of sand remaining in the bucket after being lifted 70 ft can be found by subtracting the amount of sand lost from the original weight:
135 lb - (0.5 lb/ft × 70 ft) = 100 lb
To lift 100 lb of sand 70 ft requires the crane to do work equal to:
100 lb × 70 ft = 7,000 ft · lb
Therefore, the answer is choice B, 8225 ft · lb, which is not one of the choices given.

Solve the Problem. -A Construction Crane Lifts a Bucket of Sand Originally Weighing