Why does a falling piece of toast always seem to land on the buttered side?
Why does a falling piece of toast always seem to land on the buttered side? asks a reader.
It’s the heartbreak of dropped toast. You tip your plate or lose your grip or bump the table. In the blink of an eye, your toast is, well, toast: the buttered side stuck to the floor, its surface studded with dust, grit, and cat hair.
But don’t blame the cow. Toast also lands jam-side down, peanut butter-side down, and, in the U.K., Marmite-side down.
The falling toast effect is one of the most popular examples of Murphy’s Law: that whatever can go wrong, will. People have been dropping their buttered toast on the unforgiving floor (and complaining about it) for centuries. In 1841, an Ohio newspaper called The Huron Reflector published a bread lament:
“I never had a slice of bread, Particularly large and wide, That did not fall upon the floor, And always on the buttered side.”
By the end of the 20th century, science had caught up with what the rest of us already suspected. U.K. researcher Robert Matthews conducted a scientific investigation of the dynamics of buttered toast. The result was a 1995 report in the European Journal of Physics, “Tumbling toast, Murphy’s Law, and the fundamental constants.”
In the paper, Matthews noted that the prevailing view among scientists at the time was that there was no toast problem. Like flipping a coin, toast dropped enough times should land 50 percent of the time on the plain side, 50 percent on the spread side.
And a BBC science show experiment in the early 1990s seemed to support that conclusion. Volunteers threw their toast into the air. Of 300 tosses, 152 landed butter-side down, 148 butter-side up. The conclusion: the chances of buttering your floor are about 50-50.
But Matthews found this wasn’t the case. In real life, toast isn’t tossed up into the air. Instead, it slips off a table or a plate, and usually does land on the buttered side.
How come? While it seems like the weight of the butter or other spread is to blame, Matthews says it’s the height the toast falls from that’s crucial. When toast — resting buttered-side up — slips off a standard-height table, it tends to flip over. Why? When the center of the slice — which is the center of gravity, if the toast is buttered evenly — moves beyond the edge of the table, the toast begins to rotate over the edge.
If the distance to the floor isn’t far, the toast won’t have time to do a full 360 in the air. So toast falling about 3 feet usually lands butter-side down. If the toast has far to fall, it could go either way: angular momentum will cause it to spin end-over-end, but air resistance will slow it down. And if it happens to spin, say, 1.5 times, it’s buttered linoleum all over again.
The tumbling toast effect, Matthew says, “seems to be an ineluctable feature of our universe.”
For more toast experiments, visit www.thenakedscientists.com/HTML/content/kitchenscience/exp/butter-side-down.
