This is a writing exercise for the student, and answers will vary.
Work Step by Step
Sample: Al is in an accelerating box in deep space. What experiment can he perform to tell if he is, instead, in a stationary box on the surface of a planet that pulls on him with its gravitational field? a. Drop a ball and observe its motion b. Shine a beam of light across the box and observe its motion c. Put a known mass on a sensitive scale d. None of these The correct answer is d, none of these. Einstein's principle of equivalence says that all observations, both mechanical and electromagnetic, made inside a accelerating box are exactly the same as those made inside a classical gravitational field. No measurement can distinguish between the 2 cases.