Crate moves on its own in shop

[Alchopwn]

22 hours ago, ChrLzs said:

Analysing slow frame rate footage, especially from cheap, low res cameras is VERY difficult and there are numerous traps, one of which you fell into.  Please do some deeper research.

Yeah, I see what you mean.  But that doesn't mean that there aren't some anomalies about what happened.  Firstly, I agree that there could have been a  brush of contact in the last frame you provided.  On the other hand, it would have been a tiny contact at most.  Those crates aren't exactly heavy, but are they really that light or was that floor just that slippery?  I could understand how she might not have been able to feel the impact thru her footwear, but think about how light that contact must have been for that to be the case.  I'd say the maximum weight you could kick and not notice would be about half an ounce, and that crate probably weighs about 3 pounds at least.  Given the angle she is kicking from, she won't be transferring the full force of her kick, but about 85% of it.  Now the camera angle is a bit deceptive, but I don't think you can move a 3+ pound crate with a 0.46 oz kick unless that floor is worse than an ice skating rink and the crate is greased or something.  Remember that she didn't feel making any contact with the crate, and that is what caused the "spook" issue in the first place.  Any way you slice it, that is one hell of a "snooker shot".

Edited March 30, 2020 by Alchopwn

[XenoFish]

1 hour ago, Alchopwn said:

Yeah, I see what you mean.  But that doesn't mean that there aren't some anomalies about what happened.  Firstly, I agree that there could have been a  brush of contact in the last frame you provided.  On the other hand, it would have been a tiny contact at most.  Those crates aren't exactly heavy, but are they really that light or was that floor just that slippery?  I could understand how she might not have been able to feel the impact thru her footwear, but think about how light that contact must have been for that to be the case.  I'd say the maximum weight you could kick and not notice would be about half an ounce, and that crate probably weighs about 3 pounds at least.  Given the angle she is kicking from, she won't be transferring the full force of her kick, but about 85% of it.  Now the camera angle is a bit deceptive, but I don't think you can move a 3+ pound crate with a 0.46 oz kick unless that floor is worse than an ice skating rink and the crate is greased or something.  Remember that she didn't feel making any contact with the crate, and that is what caused the "spook" issue in the first place.  Any way you slice it, that is one hell of a "snooker shot".

Not necessary. If you she thinks it is stable and goes to put her weight fully on the crate, that would be her full force pretty much hitting the crate due to the misstep. 

[ChrLzs]

And that type of crate is light, and requires little *force* (esp on a shiny, slippery floor) to move.  This happened suddenly, in a matter of a second or so - she wouldn't have been aware of exactly what happened - why must it have been a 'tiny contact'?  Plus you can see her foot is too low in all recorded frames, to have had a chance to actually land on the crate,  It could only have pushed it...

I'm sorry, but I reject your 'numbers'.  Half an ounce???  And we are not talking about weight/mass, we are talking about a transfer of *momentum* - a fast foot versus a plastic crate on a low friction surface.  If you genuinely want to try to put numbers on that, you need to use the correct physics and give error ranges and assumptions.

 

BTW, this crate is 2.8 pounds.  

https://www.richmondau.com/product/milk-crate-blue-mcr013blu/

Now we need the coefficient of friction ......

 

Well, we would if there was an anomaly worth chasing down.  I see zero anomalies.

Edited March 30, 2020 by ChrLzs

[XenoFish]

2 minutes ago, ChrLzs said:

Now we need the coefficient of friction ......

 

Grocery store floors at typically waxed. So low friction. I used to work at one. You could slide a loaded milk crate around pretty easy on it.

[drakonwick]

I feel the bottom line is either this is completely fabricated with a Monofilament string, or reality in that she misstepped on a stool and fell! I will go with the latter.