how people swim in water

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Hi guys I never learned to swim as a child, and I’ve signed up for adult swim lessons soon. Something I think will help me prepare for the lessons is I don’t know the mechanics/physics behind the motion. So I’m asking

1.) how do people float in water and why is it crucial to swimming?

2.) how do people actually move from point a to b in water while swimming?

EDIT: thanks so much to all who have responded with answers, tips, advice, and encouragement! Trying to read through all your helpful answers ☺️

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Floating is a question of density. The human body is about 70% water. Of the remaining 30% some portion of that is denser than water but there’s enough that’s less dense than water which means that you naturally float if you lie still. This is why if you ever get into difficulty just stop and relax because in a panicked state you can perform motions that cause you to dip below the water line. That fine balance is how you can dive underwater if you want to. It takes continuous effort to remain underwater as your body is naturally buoyant.

You can swim with as simply as extending your arms and moving them in circles. Due to the density difference between the water and the air you will essentially have more friction with the water than friction with the air and this will transform into acceleration through the water.

Kicking vertically with your legs will also cause you to move forwards because as you exert vertical force on the water some of it moves behind you and every force has an equal and opposite reaction and so you get some forward momentum from that as well.

You can move through the water either with your arms or legs but it’s usually more efficient to combine the two.

What I would recommend is first get comfortable floating so you know what state to return to by default. Then just make specific movements with your arms and legs and feel the effect it has. If something does something you don’t like you just stop and you will return to floating.

EDIT: If you want to dive underwater, though I wouldn’t recommend trying this until you’re comfortable on the surface, you just rise up and then use the potential energy by pushing your face down into the water. Then your lift your legs up and your stomach essentially acts as a fulcrum and then the weight of your legs pushes you further down. At this point , if you do nothing, you will float back up to the surface, so you need to to use the same surface swimming techniques to counteract that buoyancy.

Underwater you won’t have the benefit of the low air resistance for half of the stroke. So you need a slightly different technique where by you’re creating mores resistance for half of the stroke. For example turning your hands parallel to the direction of travel to move them forwards so they generate less resistance during that motion and then turn them perpendicular for the return motion so you create more resistance as you pull back.

It sounds complicated but it’s actually incredibly instinctual.

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