GED Science TestPhysical ScienceHard
A construction worker uses a pulley system to lift a heavy beam. With the pulley system, they apply a force of 200 N to lift the beam a distance of 5 meters. If the beam weighs 600 N, and the pulley system has an efficiency of 75%, what is the actual mechanical advantage of the pulley system?
- A2.0
- B3.0
- C2.25
- D4.0
Show answer & explanationAnswer & explanation
Correct answer: B. 3.0
Actual Mechanical Advantage (AMA) is calculated as the ratio of output force (load lifted) to input force (effort applied). AMA = Output Force / Input Force = 600 N / 200 N = 3.0. The distance and efficiency are distractors for this specific calculation.
Why the other options are wrong
- A. Incorrect calculation.
- C. This would be the Ideal Mechanical Advantage (IMA) multiplied by efficiency if IMA were 3 (3 * 0.75 = 2.25). But IMA is not asked, and AMA is directly calculable.
- D. Incorrect calculation, possibly confusing with IMA for a 4-pulley system or similar, but not directly from the given forces.
Actual Mechanical Advantage (AMA)
The ratio of the output force (load) produced by a machine to the input force (effort) applied to it.
- AMA = Output Force / Input Force.
- Always less than or equal to Ideal Mechanical Advantage (IMA) due to friction.
- Measures the actual force multiplication of a machine.
- Unitless value.
Memory trick: AMA: Actual Means Applied.