That's a strange question, but I hope you can help me anyway.
Brief history:
I and a friend of mine were playing Playstation together the other day. When I was briefly on the balcony to have a smoke, I complained to him about my neighbor, who placed her flowerpots unsecured on the windowsill. I live on the 7th floor!
My buddy replied that it wasn't that bad after all, and that his mother had garden gnomes on the window sill in your apartment (who the hell likes garden gnomes) and they were also unsecured.
Thereupon a discussion broke out on the said topic.
Now to my question. Suppose I live on the 7th floor, the way down is 20m and a 1kg heavy hollow garden gnome falls on the head of a passerby. This breaks on impact (the dwarf, not the head).
How much energy / weight would act on said passers-by, minus the deformation / shattering of said case object.
I could cobble together my own answer now, ala energy = mass × acceleration, but maybe one of you knows exactly.
Thank you for your answers, I created an account for this incredibly important question
That's a bit complex. Why? There are now the variants from "Pot does not break" to "Pot dissolves completely". In the latter case we can imagine that the flower pot consists only of sand that has been packed together. This then crumbles with the slightest force. In this case the mechanical effects on the head of the passer-by are likely to be negligible - the clothes would have to be cleaned.
If the pot does not break and if it does not tip sideways when it hits, the entire kin energy or the impulse goes to the passer-by and his head. The momentum now depends on the mass of the pot - - - 1kg is quite a lot.
The impact situation is not clear. Which way is the pot braked --- that is the crumple zone. Let's generously assume that the scalp serves as a crumple zone - then let's estimate 1cm. The skull is also a bit elastic - but let's not do that.
What is to be calculated?
The speed of impact (falling from 20m)
over the braking distance (1cm) the deceleration a
calculate the force with colleague Newton: F = m * a
First of all, thank you for your answer.
Unfortunately, I'm still almost as smart as I was before. To be honest, I completely forgot the braking distance. It's good that you mentioned that again.
Suppose the pot or garden gnome breaks into 9 different sized pieces at the Auprall. Is there really no way to calculate the damage or the force a little more precisely, except with a practical test. Where should I get all the garden gnomes from (let alone the heads).
Maybe someone else has a good idea, also with a precise calculation method.
You can make an approach with regard to the amount of energy that annoys the head… 0 would be the sand pot 1 the hard pot. Then take e.g. 75% on and you have a clue.
Thanks for your quick answers, you are great!
Have the whole thing calculated, it would be nice if you would look over it again.
So:
P = pulse
t = contact time (braking distance), let's say 0.5 sec.
F = force
V = speed (19.81 m / s)
M = mass (1Kg)
For the impulse: 1Kg × 19.81 m / s = 19.81 kg m / s
Now the impulse through the contact time / braking distance, i.e. 19.81 ÷ 0.5 = 39.62 N = 4.04 kg and that again multiplied by 0.75 estimated = 3.03 kg.
So the stupid garden gnome hits the passer-by with only 3kg in front of the bib, or did I make a mistake? To be honest, I was expecting a more impressive number. Well, good for all dwarf owners with a balcony
=) I think we've chewed through the subject enough by now.
Sorry… That's not right
the impact velocity is calculated as v = root (2 * g * h), that is 20m / s at a height of 20m.
If we decelerate the object to 0.01m (thickness of the scalp), this results in an acceleration of 20000m / s ^ 2. With a mass of 1kg this corresponds to a force of 20000N
Let us assume some elasticity: the head tilts forward and the body evades a little… This extends the braking distance to 10cm (which is quite a lot), then we get an acceleration of 2000 m / s ^ 2 corresponding to a force of 2000N… Actual still quite a lot for a head
