Originally Posted by With help from spacebattles(good people there)

Then we need to figure out the density, velocity, area and drag coefficient

I used a density of 1.293 because it was there. Area, I got the length from wiki

http://en.wikipedia.org/wiki/Knitting_needle by adding 4 and 15 and dividing by two, width was from here

http://www.kcgtrading.com/needles.php?type=circular again I added the highest and lowest and divided by two. Due to the wiki article listing the density or air in metres and every test and exam I’ve had in physics requiring us to work in terms of metres I converted these to metres

Length of 0.2413 metres and width of 0.01075 metres

Now to finally get the area I used the formula of the area of a cylinder pie*radius squared*height where radius was half the width and height was the length

This of course gives us an area of 2.19*10^-5m^3

While that’s useful for figuring out the energy I’ve now realised that’s not the projected area (which is all that matters for the purposes of drag (which would be pie*radius squared)), the projected area would be 9.07*10^-5m^2

For the drag coefficient I chose 0.1, lacking a reference number for needles and such, this might be lowballing it as this site

http://www.engineeringtoolbox.com/fr...nts-d_778.html says the coefficient between waxed wood and snow would be 0.04 but oh well.

Next we need to find out how much energy to ignite that wood

http://virtual.vtt.fi/virtual/innofi...g/burning.html, from here we know wood burns at 300 degrees Celsius and from here we know how many joules to raise a gram of wood one degree

http://en.wikipedia.org/wiki/Heat_ca...ding_materials. Now we need to figure out how many grams of wood we have, we know from here

http://www.simetric.co.uk/si_wood.htm the density of a variety of wood, I chose the lowest, 380,000 grams per cubic metre then times that by the area which gives us 8.32 grams of wood to raise 300 degrees Celsius (assuming a starting point of 0 of course)

8.32*0.42*300=1047 (if you were to just do that equation you wouldn’t get 1047 as it’s not exactly 8.32 grams of wood).

I wouldn't have known where to get all that material. But the rest was easy then.

Energy = Force * Distance

This is for the needle to just start burning (distance practically falls away due to needles igniting pretty much instantly after being thrown):

1047=0.5*1.293*(v^2)*0.1*(9.07*10^-5)

1047=(v^2)*(5.8678*10^-6)

174511742 = (v^2)

13210,3 m/s

47557,08 km/h

mach 39

Lowest temp for a white flame is around 1300°C, so you just need to adjust properly.