Mythbusters & Physics: Surprising Experiments

[tstrong]

The TV show Mythbusters is basically just a series of physics experiments and I'm sure the members of this forum have a better than average grasp of the physical laws that we all operate under, so my question is this: how often have you been surprised by the outcome of an experiment? What was the experiment?

 

[berkeman]

The TV show Mythbusters is basically just a series of physics experiments and I'm sure the members of this forum have a better than average grasp of the physical laws that we all operate under, so my question is this: how often have you been surprised by the outcome of an experiment? What was the experiment?

Welcome to the PF.

Note the "Related Threads" at the bottom of the page. That will give you some background.

BTW, those guys are crazy!

 

[DaveC426913]

The TV show Mythbusters is basically just a series of physics experiments and I'm sure the members of this forum have a better than average grasp of the physical laws that we all operate under, so my question is this: how often have you been surprised by the outcome of an experiment? What was the experiment?

I just saw the 'swimming through aerated water' ep, and was as surprised as they were that water filled with bubbles not only did not no make their test subject sink, but actually made it rise.

 

[Fewmet]

I was surprised by their results from testing what happens when a car drives up a ramp and into a truck in motion. I had seen this in a Bond film and dismissed it as ludicrous. I reasoned that the car tires spun fast enough for the car to go, say 70 mph with respect to the surface beneath it. I expected that, shortly after getting on the ramp, the car would move 0 mph with respect to the truck. They made it work.

For more often, though, I am irritated by poor modelling in the tests they run.

 

[DaveC426913]

I expected that, shortly after getting on the ramp, the car would move 0 mph with respect to the truck.

?? That's exactly what happened, so you expected correctly.

For more often, though, I am irritated by poor modelling in the tests they run.

They are always open to input from viewers and often revisit myths when someone points out a flaw in their tests.

 

[Fewmet]

?? That's exactly what happened, so you expected correctly.

Oops: major typo on my part. I expected the car to move at 70 mph with respect to the ramp. They showed me the error of my ways.

 

[Pengwuino]

I'm rarely ever surprised by their results. The bullet being stopped by water was surprising only for the reason I knew I had no real reason to believe it would or wouldn't travel very far in the water.

 

[mege]

I'm rarely ever surprised by their results. The bullet being stopped by water was surprising only for the reason I knew I had no real reason to believe it would or wouldn't travel very far in the water.

I find it always interesting to see some of the experiments in action - even if the results aren't suprising.

My favorites are always the idioms that they put to the test 'can't shine poo', 'lead baloon', etc.

 

[Pengwuino]

I LOVED the Confederate Rocket. That was actually surprising even though it wasn't really a physics experiment.

 

[Chi Meson]

I have watched every episode they made, just over this past year, along with my 9-10 year old daughter. I think that their layman's science is just brilliant.

But they actually have a severe flaw in that they will perpetuate misconceptions in every other episode. I can forgive them when they (including Grant) get some physics wrong in their explanations (saying "kinetic energy" when they mean "momentum"; saying "energy" when they mean "power"; saying "current" when they mean "voltage"; etc etc) but when the narrator talks over some pre-planned animated sketch and gets the physics wrong, it makes me want to hike out to California and volunteer my time to help them say it right.

That being said, I am rarely surprised by the outcomes, but always excited and amused by their arrival. [The Drop/shoot bullet experiment will be part of elementary physics classes for the next half-century.] I also play a game with my daughter in which I explain to her what the outcome should be (if it is physics related; "shining poo" was out of my area of expertise!).

 

[zoobyshoe]

I was surprised by the one where they tested the cartoon device of a character standing on a ship blowing on the sail and making the ship move forward. They did it with a fan, and, to my surprise, the ship moved forward! I thought it would stand still, that forward pressure on the sail would be counteracted by the fan trying to move the ship backward.

(Also: not physics related, but i was surprised by the elephant/mouse test. Elephants appear to be authentically afraid of mice!)

 

[Pengwuino]

But they actually have a severe flaw in that they will perpetuate misconceptions in every other episode. I can forgive them when they (including Grant) get some physics wrong in their explanations (saying "kinetic energy" when they mean "momentum"; saying "energy" when they mean "power"; saying "current" when they mean "voltage"; etc etc) but when the narrator talks over some pre-planned animated sketch and gets the physics wrong, it makes me want to hike out to California and volunteer my time to help them say it right.

That being said, I am rarely surprised by the outcomes, but always excited and amused by their arrival. [The Drop/shoot bullet experiment will be part of elementary physics classes for the next half-century.] I also play a game with my daughter in which I explain to her what the outcome should be (if it is physics related; "shining poo" was out of my area of expertise!).

Sometimes I think they have a fundamental misunderstanding of the difference between things like 'momentum' and 'force'. I've heard them consistently say things to the effect that an object going faster has more force. I wish I had been watching recently so some examples would be fresh in my mind.

I was surprised by the one where they tested the cartoon device of a character standing on a ship blowing on the sail and making the ship move forward. They did it with a fan, and, to my surprise, the ship moved forward! I thought it would stand still, that forward pressure on the sail would be counteracted by the fan trying to move the ship backward.

The thing I didn't like about that episode was that they seemed to be implying that Newton's Laws were not actually valid. Grant's explanation seemed extremely hand-waving, saying things like "the sail couldn't absorb all of the air". Absorb? What? Clearly something was going on that I want a real explanation about.

 

[zoobyshoe]

The thing I didn't like about that episode was that they seemed to be implying that Newton's Laws were not actually valid. Grant's explanation seemed extremely hand-waving, saying things like "the sail couldn't absorb all of the air". Absorb? What? Clearly something was going on that I want a real explanation about.

Hmmm. I don't remember how they tried to explain it and it seems to have been removed from YouTube.

 

[flyingpig]

https://www.youtube.com/watch?v=JisgLhWghRQ

 

[tstrong]

Thanks for the welcome Berkeman. I get surprised from time to time, the most recent example that comes to mind is the episode where they are using alternatives to cannonballs for cannon fodder. They broke up some wine bottles and shoved them down the muzzle, my mental prediction was 1/4" to 3/8" shards and reasonably effective, Nope, basically sand after it left the barrel.

 

[Chi Meson]

The thing I didn't like about that episode was that they seemed to be implying that Newton's Laws were not actually valid. Grant's explanation seemed extremely hand-waving, saying things like "the sail couldn't absorb all of the air". Absorb? What? Clearly something was going on that I want a real explanation about.

That was a good example. To his credit, Grant stated (IIRC) that he didn't quite grasp the physics, and his explanation was almost correct, but again, fundamentally flawed. To repeat, the beef I have is that the producer could have asked a half-decent High School Physics Teacher (yo!) to find out how to have the narrator say it correctly and succinctly. But instead, the "not quite getting it" standard is perpetuated as an acceptable form of information for the American audience.

 

[zoobyshoe]

To repeat, the beef I have is that the producer could have asked a half-decent High School Physics Teacher (yo!) to find out how to have the narrator say it correctly and succinctly.

So...how did it work?

 

[timthereaper]

I agree with the comments about scientific hand-waving. As a mechanical engineer, I often get a bit irritated with their explanations about why the experiment yielded the results it did. My wife just rolls her eyes when I shout the real explanation at the TV. However, I do think that the explanations need in some way to be dumbed down a bit for ratings' sake. I can imagine that a good portion of viewers are people with a very limited grasp of physics and want a more "common man's view". If that kind of person can't relate to the show on some level, why would they watch it? I would think that the producers of the show have a hard time straddling the line between pleasing the scientifically-minded and the layperson and overall, I don't think they're doing that badly.

About the explanation in the "blowing your own sail" episode, from what I understand, Grant is an electrical engineer, so fluid mechanics would be just slightly out of his field of expertise.

 

[Borek]

they (including Grant) get some physics wrong in their explanations (saying "kinetic energy" when they mean "momentum"; saying "energy" when they mean "power"; saying "current" when they mean "voltage"; etc etc

Top it with translation done by people who understand even less physics than Mythbusters do, and you will know what we are watching in Poland

 

[Fewmet]

So...how did it work?

I think you mean the fan blowing on the sail?

My high school students wrestle through that every year. I find it easiest in terms of conservation of momentum. Momentum is conserved in the closed system of the fan, the boat and all the air (including what has already bounced off the sail and passed the fan). The air that bounces off the sail has a momentum in the negative direction (if the fan is pointed in the positive direction). The longer the fan blows, the more air there is with a negative momentum, so the greater the positive momentum of the can and boat.

 

[zoobyshoe]

I think you mean the fan blowing on the sail?

My high school students wrestle through that every year. I find it easiest in terms of conservation of momentum. Momentum is conserved in the closed system of the fan, the boat and all the air (including what has already bounced off the sail and passed the fan). The air that bounces off the sail has a momentum in the negative direction (if the fan is pointed in the positive direction). The longer the fan blows, the more air there is with a negative momentum, so the greater the positive momentum of the can and boat.

Thanks much, Fewmet. I'm cogitating on this.