Science experts - what are "outside variables"?

[vettechick99]

I'm taking a research class and my first assigment is on the show Mythbusters. We have to note what the hypothesis was and how any outside variables were controlled. What exactly are "outside variables"?

 

[lisadr]

I'm taking a research class and my first assigment is on the show Mythbusters. We have to note what the hypothesis was and how any outside variables were controlled. What exactly are "outside variables"?

I think you have to tell us the experiment-otherwise that's a lot of possible variables to list.

 

[Christine]

Aren't outside variable the things outside of the experiment that you really can't control? You can try to anticipate them and allow for them but you really have no control over them?

 

[vettechick99]

That's what I was thinking. Like weather?

The experiment was to see if a tiny hole (like a bullet hole) would cause "explosive decompression" in an airplane at high altitude. Basically causing the entire side of the plane to blow out and people fall into the air.

So they took a salvaged plane and simulated 35,000 ft altitude. Then used a gun on the inside to blow a hole in the side.

What DH and I were thinking was the outside variables would be wind and temperature? And neither ended up being a factor because of where the plane was located (in a plane cemetary out west).

But am I missing the boat here?

 

[java]

Outside variables- things beyond your control that occur.
Wind the direction it is moving in , Temperature, Velocity of the plane if there was a pilot? constant vs. average, aceleration- constant or average =is the plane going up or straight, and maybe

Wind
Temperature
Weather would be the outside variables

Velocity and acceleration of the plane are things that could be controled if they had that data but they didn't take that into account according to what you wrote.

All this according to my 14 year old Physics honors student that is home sick today.

 

[lisadr]

That's what I was thinking. Like weather?

The experiment was to see if a tiny hole (like a bullet hole) would cause "explosive decompression" in an airplane at high altitude. Basically causing the entire side of the plane to blow out and people fall into the air.

So they took a salvaged plane and simulated 35,000 ft altitude. Then used a gun on the inside to blow a hole in the side.

What DH and I were thinking was the outside variables would be wind and temperature? And neither ended up being a factor because of where the plane was located (in a plane cemetary out west).

But am I missing the boat here?

Just taking a stab at this soooo...cut me some slack.

Would having or not having passenger(weight-laden vs. unladen) be a variable? Also temp., moisture. Just guessing here .

 

[luvmy3]

Wouldn't you have to take into account the cabin pressure?

 

[Cindy B]

Do you have a student science and/or chem text nearby?

My daughter just did this in her 6th grade science class, and my son did it in his 8th grade class. They both did a similar assignment on Mythbusters --actually! (6th grade it was Mythbusters, and 8th was an actual experiment the students conducted)

I remember doing it in chem class and three of my psych classes. So if you have a psych degree you can look up in your own texts for example.


What actually changes in the experiment?

What happened to the plane? (Did it crumple or stay the same?)

So are you saying there was absoluetely no wind or no temperature in this experiement?

If it was performed outside, there were weather influences (they may have been subtle though)

 

[vettechick99]

Thanks! The experiment was pretty simple - I mean there are only so many things they can replicate. Obviously the speed of the plane can't be part of it because it's too dangerous for the pilot. So some stuff they had to eliminate, and they didn't even discuss them.

All they did was worry about the pressure on the inside of the plane. And they used a huge air compressor to pump compressed air in. They also plugged any holes to make sure they could actually get to 8 psi (the pressure of a plane at 35,000 ft).

So the only other thing they could try to control is weather - picking a sunny, wind-free day. They never said this, but I can assume.

They did do the experiment with a dummy and some packing peanuts to see what would happen. Other than that, the plane was empty except for some seats.

So my answer to the question "What were the outside variables and how did they control them?" is:

weather (inlcuding wind speed, temperature, and precipitation): While they did not say specifically, the crew chose a day with low wind and no precipitation to conduct their experiment. Temperature did not seem to be a factor.

And the hypothesis they tested was "A tiny hole will cause a larger hole in a plane flying at high altitudes to explosively decompress, resulting in people and objects flying out." Does that sound good?

Thanks everyone!!!!

 

[wnissen]

"Outside variables" are those aspects of the environment that could affect the outcome of an experiment. So temperature might affect the experiment, so it's an outside factor, while the angle of the sun would not affect the outcome, so it's not an outside variable.

I think you're right that wind speed is an outside variable, but they did a poor job of controlling for it. Cruising speed for a jet is hundreds of miles per hour, so choosing a low wind day is the opposite of controlling for that variable. Ditto temperature, which is very low outside the aircraft. I may get flamed for saying this, but the Mythbusters are mediocre scientists.

Your statement of the hypothesis is pretty strong. Explosive decompression is defined in terms of the rate of decompression, so unless they measured how long it took to get down to atmospheric pressure, one couldn't say it was "explosive." I think most accurately the hypothesis would be: "In an airplane with the same pressure differential as at cruising altitude, a small hole made by a projectile will cause a large hole and decompression rapid enough to make people and objects fly out."

Walt

Walt