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The Science of Surfing

How does surfing work? It looks so easy until you try and do it yourself! Understanding the science behind surfing may help. Believe it or not, most sports involve a surprising amount of science…

To surf, you obviously need two things: waves and a surfer. To investigate the physics behind the sport, we can look at the science of each of these separately.

 

The physics of the waves

Firstly, the waves. What are waves? Where do they come from? Simple – they are formed by wind blowing over the water. The speed at which this wind blows, the distance it travels and the time it takes, all affect the size and shape of the waves. Huge waves are created by massive storms way out at sea. These are the ones that are perfect for the professional surfers. Not so good when you’re a learner!

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Why do the waves break at different times and heights? Well, the answer is in the shape of the ocean floor below the water, as well as the direction the wind is blowing at the shore. Hollow waves or tunnels are needed for the perfect surf. So the ideal conditions are a very steep slope in the ocean floor and wind blowing from the beach out to sea. The slope in the ground causes the waves to break. As the waves reach shallower water, the bottom of the wave slows down and the top of the wave then overtakes and spills over.

 

The physics of the surfer

Now, to investigate the physics of the surfer. When paddling out, the surfer is lying on their front on their board. Here, two forces are simply balanced: gravity and buoyancy. Gravity is pulling the mass of the surfer and the board down to the centre of the planet. Buoyancy is the upward force, acting opposite to gravity. It is created by still water and is also known as ‘hydrostatic force’.

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Once the surfer is standing up on their board, the most important thing to enable them to stay standing is, of course, balance! Balance means making sure the forces acting on them (gravity and buoyancy) act at the same point. As they ride a wave, the point at which the buoyancy force acts will move. It is up to the surfer to place their centre of gravity above this point to remain in equilibrium. When these forces do not align, the board will experience a torque, which twists the board. It will continue to twist until the forces are balanced again. As the surfer shifts their weight relative to the centre of mass of the board, they direct the nose of the board in any direction. This is how they steer the board.

 

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And that is the science of surfing! Easy, now you know, hey?

If you love sport and are interested in the science behind the technique, why not take Maths and Physics A-levels and see where they can take you?