228: Resonance

Explain xkcd: It's 'cause you're dumb.
Revision as of 18:13, 20 May 2013 by (Talk)

Jump to: navigation, search
It's really hard to control the frequency, actually.
Title text: It's really hard to control the frequency, actually.


Resonance is the tendency for an object to oscillate when energy is transferred to it at a specific set of frequencies (known as harmonics of the natural frequency of the object). A simple example of this is pushing a child on a swing: by pushing the child at the right moment, more and more energy is transferred to the system and the amplitude of the oscillation grows.

In this comic, the friend is jiggling his leg up and down at a harmonic of the natural frequency of Cueball's desk. This causes Cueball's desk to vibrate more and more until objects on it start to bounce around. Rather than have the friend stop, Cueball wants him to slightly increase the frequency of the jiggling in order to spill the drink on Steve's desk (which is not pictured).


[Cueball is sitting at a desk, which is vibrating.]
clatter clatter
[He leans back and turns to face someone sitting at another desk behind him.]
Cueball: Excuse me--you're jiggling your leg up and down. It's traveling through the floor and making my desk resonate.
Friend: Oh, I didn't even realize! I'll stop.
[Cueball passes a sheet of paper to the friend.]
Cueball: Actually, can you just shift the frequency up by 15%? I think you can get resonance with Steve's desk instead.
Friend: Uh huh...
Cueball: Here are the calculations. Let's coordinate and try to spill his drink.

comment.png add a comment! ⋅ comment.png add a topic (use sparingly)! ⋅ Icons-mini-action refresh blue.gif refresh comments!


How do you guys know which one is Cueball? 19:52, 10 October 2014 (UTC)

In general, the first one to talk is referred to as Cueball. 21:13, 23 March 2015 (UTC)

So, was it because his drink got spilled that Steve screwed up the calculations for the Jupiter slingshot, causing New Horizons to return to Earth (and his eventual demise under a pile of burning spacecraft wreckage)? Does this make Cueball a murderer? 11:41, 5 June 2015 (UTC)

What If? and Xkcd mention Steve and New Horizons. 22:47, 15 November 2015 (UTC)

Is there an explanation of why people's legs tend to want to jiggle like that? I get that and can never explain why. 00:56, 2 March 2017 (UTC)

Personal tools


It seems you are using noscript, which is stopping our project wonderful ads from working. Explain xkcd uses ads to pay for bandwidth, and we manually approve all our advertisers, and our ads are restricted to unobtrusive images and slow animated GIFs. If you found this site helpful, please consider whitelisting us.

Want to advertise with us, or donate to us with Paypal?