The video demonstrates a principle that allows an object to travel faster than the medium it is interacting with, specifically in a downwind direction. The presenter uses a model cart with a large wheel rolling on two smaller spools. This cart is placed on a board that is being pushed. The core concept is that when the cart is in contact with two media moving relative to each other, it can achieve a velocity greater than the relative velocity of these media. 

As the board moves, the cart moves down it at a speed exceeding the board's velocity. A key observation is that the large wheel of the cart rotates in the opposite direction to what one might expect based on the board's movement. This counter-intuitive rotation is explained by analogy to a propeller on an aircraft (like 'Blackbird'). A propeller pushes air backward, and this action allows the aircraft to move faster than the wind when traveling downwind. Similarly, the cart's wheel, through its rotation, pushes against the air (or the medium it's interacting with) in a way that propels it forward at an accelerated speed relative to the moving board.

The presenter concludes by mentioning that viewers can build similar models at home.

Veritasium

You don't actually need aerodynamics. Here I have a little cart with a big wheel that rolls on two smaller spools. And what I'm going to show is that when you have two media moving relative to one another, well then if this car is in contact with both media, it can actually move faster than their relative velocity.

So, as I push the board to the right, you can see that the car goes down the board faster than the board is moving. If you look carefully, you'll see that the big wheel isn't turning the way that the board is pushing it. It's actually rotating in the opposite direction.

That's just like the propeller on Blackbird, which pushes back against the air, and that's how it's able to go faster than the wind downwind. Now, you can build one of these cars for yourself at home, or you can build a model downwind cart.

Can something go faster than it’s pushed?

You don't actually need aerodynamics.
Here I have a little cart with a big
wheel that rolls on two smaller spools.
And what I'm going to show is that when
you have two media moving relative to
one another, well then if this car is in
contact with both media, it can actually
move faster than their relative
velocity.
So, as I push the board to the right,
you can see that the car goes down the
board faster than the board is moving.
If you look carefully, you'll see that
the big wheel isn't turning the way that
the board is pushing it. It's actually
rotating in the opposite direction.
That's just like the propeller on
Blackbird, which pushes back against the
air, and that's how it's able to go
faster than the wind downwind. Now, you
can build one of these cars for yourself
at home, or you can build a model
downwind cart.

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Can something go faster than it’s pushed?

Transcription