Veritasium Falling Ladder Problem

The demo shows two falling ladders. One hits a table and one doesn't. Which one falls the fastest (greatest acceleration)? The answer is the one that hits the table. Here's why.

Bonus. Here's a python model of a bouncing stick. I'm going to use this to build a full falling ladder model.

[robertartwohl]

It would be interesting to repeat the experiment with non-tilted rope ladders. . .

[paul]

After seing the veritasium short, I instantly understood by looking at your sketches. Good sketches are everything.
Thanks

[PhysicsLiteracyforKids]

Great Explanation! I love this problem! My students would get a kick out of this!

[michaelburns-kaurin]

Sounds good to me. After watching your video, I looked at the original video at 0.25 speed, you can see the tension.

[quickgld]

Very well explained. Didn't understand it before, but You made it clear

[rabenklang]

the key is conservation of angular momentum - the ladder experiment was created to deterime if a link from a falling chain will interact with the chain when hitting the ground or disconnects from the chain (standard textbook assumption). It is still valid for an ordanary chain, the last link does not pass any energy upwards like in this special angular formed chain.

[fizixx]

Interesting, and it will be fun to see how this works in Python.

[sosoyo]

Looking forward to seeing the Python video!

[INTEGRALPHYSICS]

I like your explanation. Very well put.

[Faux.Player]

Good explanation. I thought it was because the rungs were falling off the top of the pile which would pull on the strings, but after rewatching the video it looks like you are correct.

[youtooyoutoo]

Kudos to whoever discovered/invented this puzzle!
BTW: Looking carefully at the strings, you might notice that the strings are more precisely a little spring like, which begs another 'problem' to require recognizing a surprising effect of that subtle characteristic.

[ahmadreza]

Thanks for your explanation, 😊😊
Best wishes from Iran❤

[BenGray-fvpb]

E =m x c^2 m = E/c^2

When the ladder contacts the table, the total energy of the ladder increases. Hence, so does the mass. As the mass increases, so does the terminal velocity.

Terminal Velocity = (2 x mass x gravity / density x area x drag coefficient) ^ 1/2

[BlackStone.]

Here is the solution:

Let the distance which hit the table be S1 and other one be S2
And time taken by both respectively be x and y
To prove X<Y
=>S1<S2(given)

Now, S1=(1/2) gx²
And S2=(1/2) gy²

Since s1<s2
=>(1/2) gx²<(1/2) gy²
=>x²<y²
Hence we can say x<y

[djconnel]

"But what happens adfter the other side hits."
"It's too late ..."

This is a key point. In an undamped system, the rungs recoil, and then bounce off the table. This is a damped system, and the rungs do not recoil. So it actually does matter what happens after. In an undamped system, with elastic collisions, and a zero-mass rope, the strike of the left side will cause the left side to recoil, and it will bounce back, not at the same initial speed, but with the whole ladder having the same kinetic energy, since the earth can absorb momentum but due to its infinite mass cannot accumulate kinetic energy (E = p^2/2m).

What we know is the net acceleration of the whole latter, with the bounce, must continue to be g (or -g, depending on coordinates), the acceleration of gravity. So when the upper rungs are accelerating at a greater acceleration, then the bottom rung is accelerating at something other than g. This is due to the tension on the rope: the rope is supporting the lower rung.

If the ladder were infinitely long there would be no effect. As the remaining ladder gets shorter, the effect grows inversely proportional to the remaining ladder.

[flecktarnjames]

great explanation, greetings from Italy

[piotrl.pawlak]

That stands true only and only if the strings are of unequal lengths. Otherwise the ladders will fall at the same time.
It is one of experiments that is designed to induce thinking in science oriented brains, but for majority people will create confusion as in real life you have no useful ladders with uneven strings, or tilted rungs.

[joshuajoseph]

Wrong is an Important step in reaching right, if you're any good, you'll keep making steps.

[JonaLastname]

Very good but the rotation is not just around the center of mass because the other components right from the point of impact still have kinetic energy and thus push down on the lever as well giving even more angular momentum into the effect. Good analysis though

[bobjerk]

It's like that stick experiment that the end of the stick exceeds g.