FAA Aviation Mechanic General (AMG)Physics, Math and Fluid LinesHard
A hydraulic fluid has a density of 0.0311 lb/in³. What is the weight of the fluid contained in a 250 cubic inch reservoir?
- A3.89 lb
- B7.78 lb
- C12.44 lb
- D19.40 lb
Show answer & explanationAnswer & explanation
Correct answer: B. 7.78 lb
Weight is found using density × volume: 0.0311 lb/in³ × 250 in³ = 7.775 lb, which rounds to 7.78 lb.
Why the other options are wrong
- A. This results from using half the given volume in the calculation.
- C. This value comes from doubling the correct weight, an arithmetic error.
- D. This results from multiplying by an incorrect density value.
Density (Weight/Volume) Calculation
Density relates weight to volume: Weight = Density × Volume, commonly used to determine fluid weight in a container.
- Density is typically given in lb/in³ or lb/gal for fluids
- Weight = Density × Volume
- Density can be converted between units (lb/in³, lb/ft³, lb/gal)
Memory trick: 'Pack it in, weigh it out' — density times volume tells you the load.