# “Two cats sit on a roof. Which falls off first?”/“The one with the smaller mu.”

A popular math joke is:

*Q: Two cats are sitting on a sloping roof. Which one falls off first?A: The one with the smallest *mu.

The Greek letter

*mu*stands for the coefficient of friction. The cat with the smallest

*mu*—the least friction—will fall off the roof first. Also, cats say “mu” or “meow.”

The math joke has been cited in print since at least 1993.

Wikipedia: Coefficient of friction

A

*coefficient of friction*is a value that shows the relationship between the force of friction between two objects and the normal force between the objects. It is a value that is used in physics sometimes to find an objects normal force or frictional force, when other methods aren’t available.

The coefficient of friction is shown by f = \mu F_{n}\,. In that equation, f is the frictional force, \mu is the coefficient of friction, and F_{n}\, is the normal force.

Google Groups: eunet.jokes

Scientific…

*S.J.Soloman*

8/30/93

I apologise on behalf of my flatmate for the following…

Two cats are sitting on a sloping roof. Which one falls off first?

The one with the least mu.

Google Groups: rec.humor

Funny Name: Football Player

*D.J. Wischik*

11/10/93

(...)

Q. Two cats are sitting on a tin roof, and one falls off. Which one stays on?

A. The one with the larges mew.

(greek letter mu = coefficient of friction)

Google Groups: eunet.jokes

Just a quickie, with a longie attached

*Paul G Roberts*

6/5/94

BEWARE: Specialist Joke.

I’ve been reading this splendid forum for ooh ages now (two days) and I would like to offer up the following, which has probably been seen before.

Q: Two cats are sitting on a shed roof. Which one falls off first?

A: The one with the smaller mu.

Everything2

*Two Cats on a Roof*

(idea) by The Big D Sat Nov 13 1999 at 10:24:38

Which one falls off first?

The one with the smaller mew.

he he. ha. ahh. mm.

Well, in England, at anyrate, the Greek Letter

*mu*is used to denote the coefficient of friction.

sorry about that - have a look at some other geek jokes.

The Geek Culture Forums

Terrible Maths Joke

Posted by spungo (Member # 1089) on April 22, 2004, 09:16:

Another crap maths joke:

Two cats sitting on an inclined roof - which one falls off first?

*ans: the one with the smallest mu*

Marcus du Sautoy

@MarcusduSautoy

Two cats on a roof. Which one slips off first? The one with the smallest mu. (mu is the symbol for coefficient of friction)

7:29 PM - 14 May 2009

YouTube

*Math Jokes Explained - Numberphile*

Numberphile

Published on May 20, 2013

Some of your favourite maths jokes are dissected in forensic fashion.

2:58

“Two cats are standing on a roof. Which one falls off first? The one with the smaller mu.”

Nerdy Jokes

May 7, 2015

*A Furry Friction Funny*

By LC

Q. Two cats are sitting on a roof. Which one slides off first?

A. The one with the smaller mu!