The Science Behind: Surfing

Summer has officially begun!!


If we weren’t stuck indoors, this would be the perfect time to hit the beach.


Surfing is a popular summer sport. I’ve always wondered how people surf. I mean they ride the waves. It a human being standing on a surfboard riding a wave made of water! How is it possible for humans to ride liquid?



Let’s find out...


According to all movies I've watched that involved surfing, it seems that finding the "right wave" is quite important.


Surfing includes various physical principles—gravity, buoyancy, torque, and waves.


Gravity: We are all familiar with gravity. It is what keeps us on the ground. When surfers are out on the water, it is what pulls them downwards.


Buoyancy: Think of a rubber duck. As kids, when we played with it in the bathtub, it never seemed to sink. Sometimes, it would sink partially but never whole. The material that the rubber ducks are made of low-density material, which overpowers the force of gravity.


That same idea applies to surf. Surfboards are made of very particular materials. They are made so that the force of buoyancy overpowers that of gravity allowing it to float. However, if the surfer just stays still on the surfboard it is likely that soon gravity will take over and pull the surfer underwater.


When surfers are waiting for the right wave, other waves are still passing under them causing them to move up and down and helping the force of buoyancy be stronger than gravity. Even when surfers are sitting on their boards waiting for their waves, there are a lot of forces at work.


Catching waves is another surfer-like wave term. What does it mean?

The surfers start by lying on their boards. As a "good wave" starts coming in, the surfers will paddle towards the wave. According to Newton's third law, as the surfers push the water back an equally strong force will push the surfers forward.


How do surfers stand up on the waves?

As the surfer reached the bottom of the wave, the water will push the surfer upward. This hydrodynamic force will give them speed as they jump up to a low crouch to follow the wave. Surfers need to constantly adjust their wight to keep their balance.



Torque is essential to understand when surfing. When gravity pulls the surfer down and the board pushed upwards, they are acting in opposite directions. The board tries to rotate sideways due to the motion of the waves. Any force that tries to create a rotation like that is known as torque.


Surfers are constantly battling the chaotic motion of the waves. This is why they must apply their body mass to the opposite side to cancel out the weight to the torque and avoid a splash.



How do the surfers stop or slow down their boards?

Usually, the surfer will stand in the center of the board, at the center of gravity. However, when a surfer needs to stand on the back half of their board in order to slow down. As soon as the surfer changes their position to the back of the board, the strength of the buoyancy force changes to the newly submerged part of the board. This change continues until the gravitational force and the buoyant force usually balance out, eliminating the torque but now giving way to a new form of equilibrium. This setup is helpful for braking since the board is now lowering vertically into the water, which builds resistance to water flow.




Surfers are stereotypical jocks. In movies, we see the surfers as the ones who skip school or spend all their time goofing around. Contrary to popular belief, surfers actually need to have a strong grasp of physics to be good at the sport.


So if you ever need a crash-course on physics, no one better than a surfer.


Until next time...


Stay Curious ;)

Love,

Sarah




Sources:

http://www.bbc.com/earth/story/20170622-the-incredible-science-of-surfing-and-waves#:~:text=Waves%20are%20formed%20in%20a,the%20wind%20to%20the%20wave.&text=%22To%20surf%20waves%20at%20Nazare%20is%20an%20honour.%22


https://magazine.scienceconnected.org/2017/10/waves-physics-science-surfing/




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