1. The problem statement, all variables and given/known data Which of the following sets of equipment cannot be used to measure the local value of the acceleration due to gravity (g)? (A) A spring scale (which reads in force units) and a known mass. (B) A rod of known length, an unknown mass, and a stopwatch. (C) An inclined plane of known inclination, several carts of diﬀerent known masses, and a stopwatch.← CORRECT (D) A launcher which launches projectiles at a known speed, a projectile of known mass, and a meter stick. (E) A motor with a known output power, a known mass, a piece of string of unknown length, and a stopwatch 3. The attempt at a solution I eliminated A because that is a fundamental way to measure gravity, as a scale reads normal force. Simply place an object on flat ground where Normal force = mg, divide the known normal force by the known mass, and we have gravity. I eliminated B since we can use uniform accelerated motion. Δy = v_0t + 1/2at^2 since v_0 = 0 Δy = 1/2at^2, we also know t, so clearly we can find a C I believed you could find, I'm not sure why you can't. D I thought you could use projectile motion equations. E I'm not sure.