A crane is lifting a 8,000-pound load with a 4-part line (4:1 mechanical advantage). If the crane's load block weighs 500 pounds, what is the total load on the crane's hoist line?
Correct Answer
B) 2,125 pounds
Total load = 8,000 lbs + 500 lbs load block = 8,500 lbs. With a 4:1 mechanical advantage, the hoist line load = 8,500 ÷ 4 = 2,125 pounds.
Why This Is the Correct Answer
When calculating hoist line load with mechanical advantage, you must first determine the total load being lifted, which includes both the actual load AND the weight of the load block itself. The total load of 8,500 pounds (8,000 + 500) is then divided by the mechanical advantage ratio of 4:1. This gives us 8,500 ÷ 4 = 2,125 pounds on the hoist line.
Why the Other Options Are Wrong
Option A: 2,000 pounds
This answer only accounts for the 8,000-pound load divided by 4, but fails to include the 500-pound load block weight in the calculation.
Option C: 2,250 pounds
This answer appears to add the load block weight after applying mechanical advantage rather than including it in the total load before dividing by the mechanical advantage ratio.
Option D: 8,500 pounds
This is the total combined weight before applying mechanical advantage, but ignores the 4:1 reduction provided by the pulley system.
Memory Technique
Remember 'TOTAL first, DIVIDE second' - always get the complete weight before applying mechanical advantage.
Reference Hint
Look up crane operations and rigging calculations in the construction safety or equipment operation chapters of your contractor reference manual.
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