Final answer:
In an elevator in free fall, you would weigh nothing because both you and the elevator are accelerating at the same rate due to gravity, causing a scale to read zero and making you feel weightless.
Step-by-step explanation:
If you were to weigh yourself in an elevator that is in free fall, compared to your ordinary weight, you would weigh nothing. This seemingly odd situation occurs because you and the elevator would be accelerating downward at the same rate due to gravity, which is approximately 9.8 m/s2. As a result, the scale would not be able to exert an upward force to counteract the pull of gravity, and thus it would read zero, indicating you are weightless. This sort of environment, often referred to as microgravity, is similar to what astronauts experience in space and is used by NASA for training purposes aboard special aircraft designed to simulate free-fall conditions.