Elevators

A few days ago at work I was talking to someone about elevators and the question was asked, given that elevators have a counter weight, does it take more energy to move up or down? This question, of course, pertains to a roped elevator because piston elevators by design will use more energy pushing up a floor. According to this explanation at HowStuffWorks.com, the counterweight is usually set to match the car at 40% capacity. So, if the car is less than 40% full, it will actually take more energy to lower the car than it would to lift it.

I actually learned a few other things in reading about elevators on Wikipedia and HowStuffWorks.com. I'll summarize:

1. Old elevators were friggin' dangerous and had crappy controls.

2. Elevators have remained relatively unchanged over the years with two basic functional designs.

3. The most modern elevators have fancy compound pulley systems, direct drive motors, complex logic controls (like heuristics algorithms) and electromagnetic safety equipment. Basically, some of these elevators are smarter than many of the people that ride in them.

4. Even the best designed elevator breaks. That's why PM's or routine inspections are required by law in almost every area.

By the way, if you happened to be in an elevator that was hurling towards the ground and all the safety equipment failed. Jumping at the last second would not work because (1) how the heck are you going to know when the last second is unless you're in a glass elevator?, and (2) you'd have to overcome the downward velocity of the elevator which is 9.8m/s^2... you know, gravity. Here's a test. Jump as high as you can. See how long you can stay off the ground. Let's say you're Mr. Amazing and can stay in the air 3 seconds. That means you were traveling upwards for 1.5 seconds. That's the maximum time your elevator could stay in free-fall and your jump would be effective. Good luck. I think the Mythbusters covered this. Your best bet is sitting on the floor with your head between your legs... so you can kiss your butt goodbye.