The design and operation of machines and mechanical systems. Fundamental laws of motion belong in Physics.
Test your knowledge with these top questions!
Which inventor made elevators safer with a brake that caught the car if its lifting rope broke?
Otis demonstrated the brake by having the rope cut while he stood on a raised platform.
At which parts of an escalator do the steps flatten into a level platform?
Separate tracks guide each step's front and rear wheels, changing its position while keeping its standing surface level.
In a hydraulic elevator, what pushes the car upward?
A pump forces oil into a cylinder to raise the piston; releasing the oil lets the car lower under its own weight.
What do the teeth of an escalator's comb plate fit into?
The comb plate bridges the small gap between moving steps and the fixed landing, helping keep objects from entering.
An escalator's handrail is designed to move at about what speed compared with the steps?
The moving rail lets riders keep a steady grip as they travel, without sliding a hand along a fixed rail.
As a cable-driven elevator car rises, which way does its counterweight move?
The counterweight balances much of the car's weight, so the motor needs less effort to move the car.
What usually links an escalator's steps so they move together around a loop?
After riders step off, the steps travel upside down beneath the visible staircase on their return trip.
In a passenger elevator, what is the compartment that carries people called?
The car travels inside a vertical shaft, with guide rails helping it stay aligned.
What does pressing the button on a typical aerosol can do?
A spring closes the valve when the button is released, sealing the remaining contents inside.
Which once-common aerosol propellants damage Earth's protective ozone layer?
Sunlight breaks CFCs apart high in the atmosphere, freeing chlorine that can destroy ozone molecules.