# Using a Digital Balance to Measure the Travel Distance of an Elevator

Fun physics questions are fun. Here’s one for you. Imagine you have a block of aluminum on a digital scale such that it reads 102 grams. The scale is on the floor of an elevator and someone pushes a button for a floor (not saying what floor). After the doors close, the elevator accelerates and the scale reading changes (see my previous post on a scale actually tells you).

Here is the actual experiment.

There are two questions. Did the elevator travel UP or DOWN? How far did the elevator travel?

I’m going to answer the first question first — since it’s the easiest. If you watch the video, the scale reading starts off at 102 grams. When the elevator starts to move, the reading jumps to 109 grams (or something like that) then back to 102. When the reading increases, the elevator is accelerating UP and then it reaches a constant speed. Since the elevator was at rest and accelerating up, the elevator must be moving up. It traveled to a higher floor.