Measuring the acceleration of an elevator by using the apparent weight of an object inside it

Abstract

An accelerating elevator changes the apparent weight of any object inside it from the original weight, as measured inside the elevator, because the acceleration causes an inertial force on it. For any object in a running elevator, the variation of the acceleration of the elevator causes the variation of the apparent weight of the object. We have studied the time dependence of the apparent weight of the object and thus the acceleration of the elevator. For chosen initial and final floors, we measured the apparent weight of an object by using an electronic scale inside the elevator, and shot the readings of the scale and a watch during the movement of the elevator. Then we analyzed the data collected from the recorded video. If the initial and final floors are exchanged, the variations of the weight and acceleration are, respectively, same in magnitudes and opposite in signs. The experiments indicate that for the elevator to go directly from a floor to another, the process consists of periods with variable acceleration, constant acceleration, uniform motion, variable deceleration, constant deceleration and variable deceleration consecutively. If there are pauses during the movement, each pause causes an additional process consisting of periods with deceleration, stop and acceleration, replacing the original period of constant motion. Depending on the distance to the destination, the elevator reduces or diminishes the periods of constant acceleration and uniform motion.