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100
This device steps grid voltage up or down using two coils around an iron core.
What is a transformer?
100
This heavy spinning wheel stores energy and smooths out an engine's power pulses.
What is a flywheel?
100
Websites store this one-way scrambled version of your password.
What is a hash?
100
Satellites in this orbit circle Earth once a day and appear fixed in the sky.
What is geostationary orbit?
100
This Swedish company's flat-pack furniture comes with instructions that use no words.
What is IKEA?
200
MRI coils are cooled with liquid helium so they become these, with zero resistance.
What are superconductors?
200
Backspin creates a pressure difference that curves a ball's path.
What is the Magnus effect?
200
This small, ultra-fast memory on the CPU holds frequently used data.
What is cache?
200
Winglets reduce this type of drag, which comes from swirling wingtip vortices.
What is induced drag?
200
The QWERTY keyboard layout was originally designed for this machine.
What is the typewriter?
300
This law says the current flowing into a junction equals the current flowing out.
What is Kirchhoff's current law?
300
This ideal engine sets the maximum possible efficiency of any heat engine.
What is the Carnot engine?
300
Turing's 1936 model, a tape plus a read/write head, defines what's computable.
What is a Turing machine?
300
This minimum-fuel elliptical orbit carries spacecraft from Earth to Mars.
What is a Hohmann transfer orbit?
300
Ernő Rubik invented his cube in 1974 while teaching this subject.
What is architecture?
400
A conductor carrying current in a magnetic field develops a voltage across its width.
What is the Hall effect?
400
Low pressure near a propeller forms vapor bubbles that collapse and pit the metal.
What is cavitation?
400
This unsolved problem asks whether problems that are quick to check are also quick to solve.
What is P vs NP?
400
This measure of rocket engine efficiency is expressed in seconds.
What is specific impulse?
400
Bubble wrap was first invented in 1957 as a failed version of this home product.
What is textured wallpaper?
500
At high frequencies, AC current crowds toward a wire's outer surface.
What is the skin effect?
500
This ratio of inertial to viscous forces predicts whether flow is laminar or turbulent.
What is the Reynolds number?
500
CPUs guess which way an if-statement will go and run ahead before they know.
What is branch prediction?
500
Shaping a plane's cross-section smoothly from nose to tail cuts transonic drag. Name the principle.
What is the area rule?
500

This is the only letter that doesn't appear in any U.S. state name.

What is Q?