The Science Behind Spilt Coffee

It happens to me every day in the dining hall.

I get my cup of coffee and I start walking to my table; when all of the sudden my beautiful beverage begins to spills. It begins to sway back and forth and spill on to the floor (and sometimes if I am having a bad day, it will spill onto my shoe).  Yet, not only does it spill on the floor but it begins to burn my hand.

Every time this happens I think to myself, why does this happen? How can I stop it from happening to me? 

The struggle of spilling your coffee 

I ultimately resort to holding the coffee cup further from my body. However, I knew there had to be some science behind it (I mean there is science for everything).

So I looked it up on the internet and sure enough there are scientists that have research this topic.  They believe they have discovered reasons for why we spill our coffee and ways in which we can lessen the likely hood of spilling large amounts of coffee.

*Warning: this blog post may contain some highly educational big science words. The blogger will do her best to provide resources to understand the material. However, if there are any terms that the reader may not know please seek professional help. This blogger is not licensed in teaching nor understanding big physics terms.

The Experiment 

In 2011, Rouslan Krechetnikov, a mechanical engineer at the University of California and his graduate assistant, Hans Mayer,  were at a fluids dynamics conference when they noticed the participants were having a hard time carrying their coffee without spilling it. They realized that this everyday problem could be an opportunity for an experiment; however, the physics was not easy. 

From the beginning of the experiment, they realized that the spillage depended on a person's ability to walk.  And a person's ability to walk depends on different variables: their age, health, gender and variables.  

They then realized that "science of sloshing" was another key variable to their research.   However, this science depends on the complexity of accelerations, torques, and forces.

To perform the experiment,  Krechetnikov and Mayer asked a volunteer to walk at different speeds along a straight path with a filled coffee mug in hand.

According to a sciencemag article, "The volunteer did this in one of two ways-either focusing on the coffee mug, or looking straight ahead. A camera recorded the person's motion and the mug's trajectory, while a tiny sensor on the mug recorded the instant of spillage." 

The Insights 

Their discovery showed that a fluid has a natural frequency that is produced due to the size of the cup.   This means that just a person walking, without any form of interference, is going to make coffee "oscillate," or swing back and forth, in the container. 

They found that there were three key factors to spilling: the amount of the liquid, the size of the cup and the speed in which a person is walking. 

How To Prevent The Catastrophe

We may not be able to stop this horrifying situation (the spilling of the coffee); however, science has found ways to lessen the amount of coffee spilled. 

First, you can begin by walking slower. Instead of speed walking to your location slow down The slower the acceleration the better.  

Second, decrease the amount of the liquid in your container. (But who really wants to decrease their coffee intake?)

Third, hold your cup with a "claw" grip. This is when you grip the rim of the cup from above. Jiwon Han, a South Korean physics student, performed similar research as Krechetnikov and Mayer . However, he learned that using the "claw" grip lessens the movement of a person's wrist, which then reduces the oscillation of the liquid. 

The "claw" grip 

Fourth, Han also suggest getting a coffee beverage that has more foam, such as a latte.  In a Washington Post article, he says the foam is very effective at dampening the oscillation of the liquid. 





Finally, you can also use a lid on your cup in order to help prevent yourself from spilling your coffee.

Conclusion 

It might seem strange there is science that goes into spilling your coffee or that physicists actually perform research on this topic. However, their research is influencing more than just coffee drinkers.   

Jiwon Han said that his research has applications in other aspects of society.  For example, he believes his findings will help to prevent oil from spilling in a fuel truck.  

So when you go back to work on Monday, you can now impress your coworkers with your knowledge on the science behind spilled coffee.