Efficiency of Energy Transfer in Swimming: Wall Kicking vs. Water Kicking

[dibilo]

Homework Statement

When a swimmer kicks the wall at the end of a swimming pool, he tends to travel further than those who does not kick the wall but applied the same amount of force kicking in water. Why?

Relevant Equations

Sorry really have no idea

This isn't a homework but a discussion between my buddy and me. My hypothesis is that when I kicked against the wall, there is more efficiency in energy transfer, CPE --> KE than when I kick in water.

His idea is that when kicking the wall, it is a more inelastic collision and when kicking in water, it is a more elastic one.

May I know whose idea is correct or are we both correct or are we both wrong?

Thanks a lot!

 

[haruspex]

Neither, though arguably your view is closer.
Think about where the energy goes in the two cases.

 

[berkeman]

His idea is that when kicking the wall, it is a more inelastic collision and when kicking in water, it is a more elastic one.

When you push off the wall (not kick off the wall) and streamline correctly, you are moving faster through the water than you can swim, at least for a few meters. That is why you stay in the streamlined position for a few moments until your speed comes down to where it is equal to what you can maintain with your strokes.

https://blog.myswimpro.com/2022/11/22/how-to-push-off-the-wall-in-swimming-5-mistakes-to-avoid/

 

[Lnewqban]

The wall is a solid support and the leg muscles used are the same that allow us to squat.
The water offers a drag resistance to the movement of the feet and lower legs, which is proportional to the square of the velocity of those respect to the water.
We could say that the mass of water surrounding your feet and legs is a support that moves away as you try to push on it, but that it moves less and supports more the faster you can push it.

Using the proper technique, the feet and legs try to quickly push aft as much mass of water as possible.
In that process, any lateral and forward movements only induce turbulence, which wastes muscular energy.