The Hidden Physicist
Whenever you go to the beach, there is so much to look forward to! One of the many things you can enjoy while on the beach is surfing. But did you know that surfing has a lot of physics behind it? All sports have laws of physics behind them, and surfing is no exception. Everything about it, from catching the perfect wave to staying afloat, relies on physics. The process starts as soon as your board touches the water.
The board’s size and construction (which is light and less dense than the water underneath) allow it to displace water. Meanwhile, a buoyant force equal to the weight of the displaced water pushes upwards, counteracting you and the board’s weight. This lets you stay afloat and paddle while you wait for the perfect wave. Newton’s first law of motion states that moving objects don’t spontaneously speed up, slow down or change direction, and a body at rest stays at rest unless acted upon by an external force. This makes it extremely important to paddle.
As for all other waves in physics, ocean waves represent a transfer of energy. Wind accelerates particles on the water’s surface, which leads to ripples that form waves. This is further acted upon by gravity, which tries to make the surface flat again. As the waves move, particles push and pull on the other particles near them through wave-induced pressure. This motion propagates energy through the water, along with the wave motion.
Near the shore, the shallower seafloor restricts the motion of the waves. This makes it occur in a more limited region than it usually does out at sea. The wave energy gets concentrated near the surface. The waves get refracted and become parallel to the shore if the shoreline is even and smooth. When the waves get closer, you have to pivot your board in the same direction as they are in, and paddle to match its speed. Your board forms an angle with the water, which exerts a dynamic pressure (kinetic energy per unit volume of fluid) on the bottom of it. This pushes you and your board out of the water, and you can go along its surface. As you lean forward, the momentum makes you stable. Through this, you can stand up and surf along the waves. This means that you’ve caught the wave!
The fins on the board allow you to keep changing your speed and direction. Above you is the wave’s crest, where the water particles are going through their greatest acceleration. This makes them faster than the wave underneath, so they can go ahead before being taken over by gravity. This forms the curls of the waves, as they break along the shore. You would never have thought surfers are hidden physicists!
Kavya Malik, 8B