FAA Aviation Mechanic General (AMG)Physics, Math and Fluid LinesHard
A tool falls freely from a maintenance stand and strikes the floor after falling 64.4 feet. Using the formula d = ½gt² with g = 32.2 ft/sec² and ignoring air resistance, how long did the tool take to fall?
- A2.0 seconds
- B4.0 seconds
- C1.0 second
- D1.41 seconds
Show answer & explanationAnswer & explanation
Correct answer: A. 2.0 seconds
Rearranging d = ½gt²: t² = 2d/g = (2 × 64.4)/32.2 = 128.8/32.2 = 4. Taking the square root, t = 2.0 seconds. This is the standard free-fall equation relating distance, gravitational acceleration, and time.
Why the other options are wrong
- B. This mistakenly uses t = t² without taking the square root.
- C. This underestimates the time by ignoring the correct factor of 2.
- D. This is the square root of 2, not the correct value of 4.
Free Fall Distance Formula
For an object falling freely under gravity from rest, distance equals one-half the acceleration due to gravity times time squared: d = ½gt².
- g ≈ 32.2 ft/sec² near Earth's surface
- d = ½gt² (starting from rest, no air resistance)
- Solve for t: t = √(2d/g)
Memory trick: 'Half gravity times time squared' tells you how far it drops.