PDA

View Full Version : Stone and height


farnoosh777
Dec 20, 2011, 04:11 AM
If drop down an stone -that it is like a ball- into the slush and if it was soft enough stone come into the slush in some distance, if throw it away from a certain height to comes into slush and if we want stone to come into slush 2 times more than before from what hight should we throw it away?

smoothy
Dec 20, 2011, 07:23 AM
You can throw a rock into the slush as many times as you want from any height.

As it is currently worded... its not clear exactly what you are asking because it doesn't make a lot of sense.

Perhaps if you can try rephrasing it... (yes Its clear english is not your first language) then maybe we can understand better.

ebaines
Dec 20, 2011, 08:39 AM
I think the OP is asking about the relationship between how high you drop a stone to how far into a pile of snow (or slush) the stone penetrates.

The kinetic energy of the stone is proportional to the height of the drop. This KE must be absorbed by the snow as it slows the stone. If we assume that the resisting force is proportional to the distance the stone penetrates (due to compression of the snow as it packs in front of the stone), then the energy absorbed by the snow is proportional to the square of the distance it penetrates. Hence to get the stone to penetrate twice as far it must hit the snow with 4 times the KE, so you must drop it from 4 times the height.

Mojtaba7
Dec 25, 2011, 09:48 AM
Farnoosh vagean barat moteasefam ke omadi soalaye shrifo inja miporsi! On soala vase ineke maghzeto be kar begiri va haleshun koni na in ke biay inja beporsi! Vali damet garm on soal nujumo naneveshte budam! ;)