Q: Would you rather land on water or marshmallow?

[Dale]

But is marshmallow springy …

does it return to its original shape?

If not, then "spring constant" isn't the issue.

A spring absorbs energy, and then returns it …

a "crumple zone" absorbs energy, but keeps it …

I thought that was why MattSimmons chose marshmallow in the first place?

That is why I assumed a constant rupture force rather than a spring model.

 

[Ranger Mike]

i can stop by the local Tractor Supply store and pick up some 1/2 inch washers..these are about the size of a half dollar. if i stack these , one a t a time, we should see when the marshmellow collapses ..this the stree ruoture rate you were talking about?
any other advise on method to use?
freeze um first?
do i need my infrared pyrometer too?

 

[DyslexicHobo]

But is marshmallow springy …

does it return to its original shape?

If not, then "spring constant" isn't the issue.

A spring absorbs energy, and then returns it …

a "crumple zone" absorbs energy, but keeps it …

I thought that was why MattSimmons chose marshmallow in the first place?

So it would be a landing zone that doubles as a trampoline! Sounds fun! :P

 

[tiny-tim]

rupture force

Hi DaleSpam!

That is why I assumed a constant rupture force rather than a spring model.

ah, i missed that … you posted it just before my last post

but what is rupture force (it doesn't sound very nice )?

i wiki'ed it, but couldn't find anything.

So it would be a landing zone that doubles as a trampoline! Sounds fun! :P

hmm … that's what was bothering me …

falling 20,000 feet onto a trampoline doesn't seem much better than crashing!

boinggg! boinggg! ​

 

[Dale]

but what is rupture force (it doesn't sound very nice )?

It is point number 3 on this http://en.wikipedia.org/wiki/Stress-strain_curve" (Figure 1). Basically, it is the point where the material breaks, complete failure.

So, to measure it you would push on a marshmallow until it failed and measure the force and the area that you were pushing.

 

[tiny-tim]

rupture force and viscosity

It is point number 3 on this http://en.wikipedia.org/wiki/Stress-strain_curve" (Figure 1). Basically, it is the point where the material breaks, complete failure.

So, to measure it you would push on a marshmallow until it failed and measure the force and the area that you were pushing.

ah … got it!

so below the rupture force, the marshmallow will act to some extent like a spring, returning MattSimmons upward with a fairly high overall deceleration,

but beyond the rupture force, the marshmallow will continuously give way, providing a relatively safe steady viscous deceleration?

hmm … so now we also need to know the viscosity of marshmallow?

and presumably it would help to be covered with chocolate, or with some other material that will reduce marshmallow drag? ​

 

[Ranger Mike]

those marshmallows are tuffer than I thought. got a bag of Wal-Mart Great Value Marshmallows..these are the biggies..weigh 6 grams, 3 mm tall 30.2 mm diameter
did the measurements when they were 64 degrees..were in trunk over night
I stacked various washers on top until one side of the marshmallow wall gave in..I was not yet able to load the marshmallow to blow it out.total collapse.
in fact , I was only able to load 540 gram max load and the darn thing still did not fail to return to 3 mm height after load. I have to find some bar stock of sufficient weight to mash it
the height is from edge of a dished washer to the desk top and measured with a pocket scale ..note i used the slider bar on the pocket scale


the following was with washers perfectly balance

load - height mm
0 - 3.0
50 - 2.8
85 - 2.4
102 - 2.2
150 - 2.1
215 - tilt, side wall failure


I has to steady the washers by holding them so side wall would not collapse

load - height in mm
0 - 2.2
140 - 2.0
210 - 1.8
280 - 1.7
540 - 1.3
824 - 1.2

 

[Dale]

those marshmallows are tuffer than I thought. got a bag of Wal-Mart Great Value Marshmallows..these are the biggies..weigh 6 grams, 3 mm tall 30.2 mm diameter
did the measurements when they were 64 degrees..were in trunk over night
I stacked various washers on top until one side of the marshmallow wall gave in..I was not yet able to load the marshmallow to blow it out.total collapse.
in fact , I was only able to load 540 gram max load and the darn thing still did not fail to return to 3 mm height after load. I have to find some bar stock of sufficient weight to mash it
the height is from edge of a dished washer to the desk top and measured with a pocket scale ..note i used the slider bar on the pocket scale


the following was with washers perfectly balance

load - height mm
0 - 3.0
50 - 2.8
85 - 2.4
102 - 2.2
150 - 2.1
215 - tilt, side wall failure


I has to steady the washers by holding them so side wall would not collapse

load - height in mm
0 - 2.2
140 - 2.0
210 - 1.8
280 - 1.7
540 - 1.3
824 - 1.2

How big are the marshmallows? 1" in diameter by 1" tall? If so, using 215 g/in² (most marshmallows will probably fail this way rather than rupture), and a surface area of .7 m² (good for 74 kg adult male, so a little conservative for a 100 kg man) we get a revised force of 2300 N which is a little more than double my previous guesstimate. So 180 kJ/2300 N = ~ 80 m. Multiply by a factor of 2.5 for safety and call it 200 m of marshmallows.