## Udder Impossibility

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The physics of cow tipping stand on shaky ground

A cow turned force diagram from Boechler’s paper. Courtesy of Margo Lillie and Tracy Boechler.

Bessie can finally sleep in peace. A University of British Columbia (UBC) undergrad recently revealed that, according to her calculations, cow tipping is an impossible feat for four people, let alone a single drunken rural teenager.

Tracy Boechler, a recent graduate of UBC who is now training to be a police officer with the Royal Canadian Mounted Police, wrote the paper for a class called “Zoological Physics.” She said she investigated the cow tipping myth because she suspected it might not hold up.

“When you think about it, the cows are at least 1,500 pounds, so it seems very unlikely [that a person could tip one],” she said via e-mail.

Limited by a dearth of observable cows in the greater Vancouver area, she modeled the cow as a 1,500-pound rigid rectangular prism, excluding mass from the head, tail and legs, and used Newton’s laws to calculate the necessary force.

So, how many people should you invite to your next cow-tipping party? If you can bind the cows legs together, you’ll need a mere three people, assuming each person can push with a force of 150 pounds. For an unsuspecting cow standing normally, you’ll need 4.4 people and for a cow smartly bracing herself, you’ll need to muster 5.75 willing tippers.

And that’s just for the ideal rigid cows that graze in the green pastures of physics-land. In reality, they’re even harder to tip.

In her calculations, Boechler assumed the friction between hooves and the ground would be great enough that the cow would rotate around the outside edge of its hooves without slipping. Boechler set up her problem so a hypothetical pusher applied maximal rotational force, or torque, to the cow.

But, “cows are soft and a lot of the force applied will be absorbed by the cow, and more force will be required,” Boechler said. “Cows also do not seem to sleep soundly while standing up, hence they will likely wake up from their nap and either brace themselves for protection or trot away.”

These results matched the experience of at least one attempted tipper.

“Cows are heavy, man!” said Peter Park, a college student who tried to cow-tip on a trip to central Illinois. “There were four of us, but we had to run at the cow from 30 feet away and push as hard as we could to get it to even notice us. It woke up and looked at us like we were a bunch of flies, and walked away.”

Margo Lillie, Boechler’s professor and supervisor, said the only successful tipper she has spoken with used a different technique from the one addressed in the paper.

“He’s being either more clever, or perhaps more stupid, depending on the way you look at it,” Lillie said. The man who tipped had people push on both sides, one side from higher up on the cow and one from by the cow’s feet.

“He said it worked like a charm and they got the cows down…But, you know, he might be up for a Darwin Award!” she said. “You have to change the physics, I think, in order to get around the biology.”

Originally published November 18, 2005

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