Gerrit Blank, 14, was on his way to school when he saw “ball of light” heading straight towards him from the sky. A red hot, pea-sized piece of rock then hit his hand before bouncing off and causing a foot wide crater in the ground.
The teenager survived the strike, the chances of which are just 1 in a million – but with a nasty three-inch long scar on his hand.
He said: “At first I just saw a large ball of light, and then I suddenly felt a pain in my hand. “Then a split second after that there was an enormous bang like a crash of thunder. The noise that came after the flash of light was so loud that my ears were ringing for hours afterwards. When it hit me it knocked me flying and then was still going fast enough to bury itself into the road,” he explained.
Scientists are now studying the pea-sized meteorite which crashed to Earth in Essen, Germany.
This article mentions other close encounters of the outerspace rocky kind. The kind that brought life here to Earth?
Sheesh, talk about splitting hairs. This story has a relevancy facor pretty damned close to zero. What’s really interesting is watching you guys count the fairies dancing on the head of a pin.
# 41 amodedoma said, “Sheesh, talk about splitting hairs. This story has a relevancy facor pretty damned close to zero.”
Which is why you are commenting on it.
BTW – Shouldn’t you be eating lunch? I miss 2-3 hour lunches…
#30, #32, it’s not F=MA, it’s KE = 1/2 * M * V^2
# 43 BubbaRay said, “#30, #32, it’s not F=MA, ”
It is if you are calculating Force…
Okay, the real question is… would that projectile be able to make a 1 foot wide crater in the road.
We don’t know the mass of the projectile, we don’t know the surface material of the road so we have to make some reasonable assumptions.
Let’s assume that the pea sized piece of nickel or iron (it was magnetic) weighed 40 grains (2.59 grams). I used the formulas found here
http://foros.net/viewtopic.php?p=6467&mforum=Forodeltirador
to calculate the momentum and force on impact.
40 grains moving at 44000 ft/sec = 7.81 slug ft/sec
divide that number by the time to stop and you get lbs of force (at sea level)
The time to stop was 44000 ft/sec X 12 (gives inches/sec), =528,000 in/sec. If the foot wide crater was 4″ deep, time to stop is (1 / 528000 X 4) .0000072 seconds.
So, 7.81 slug ft/sec / .0000072 = 1.08 million lbs of force concentrated on a pea sized surface area.
If the crater was 6 inches deep, the force on impact was 723 thousand lbs.
JimR…but is it moving that fast after a mile or so of atmosphere?
#46 That would be ~30,000 MPH. Pretty damn fast. I guess it would depend on the speed at atmos entry and its mass & composition. If it did hit his hand, he would no longer have one.
Olo Baggins and Patrick, I was going by the title of the actual article which said 30,000 mph. they may have arrived at that number by reverse calculating the final size of the meteorite and the depth of the dent (technically can’t be called a crater)… but I suspect that a reporter messed up and was used entry velocity.
I love this stuff, so I googled it again and found out that entry speeds into the earth’s atmosphere ranges from 23,000 mph to 160,000 mph. from there they lose mass and decelerate at various rates depending on a load of factors. The smaller the final asteroid, the slower the terminal velocity… 500 km/h for a small one to 60,000 km/h for the 70m wide asteroid that made the Arizona crater.
So I guess the article is in error. 500 km/h = 310 mph … a tad off eh?
Recalculating for a 3 gram asteroid making a 1″ dent… 512 lbs of force. Sigh.
As Density was not given, your calculi is in vain.
#44, you are not calculating force, since the A in F=MA would be 1g. Not much force. You are calculating the energy released by the collision, the kinetic energy of the meteorite. A ball bearing dropped from the top of the Empire State building will reach terminal velocity, and certainly won’t blow a large crater in the tarmac. Now if it were traveling at 30,000 MPH, …
# 50 KD Martin said, “#44, you are not calculating force, since the A in F=MA would be 1g.”
Nope. It would be whatever A is. Hint, acceleration can be up or down…
#49, the density of iron is 7.89g/cm3, and nickel is 8.19g/cm3. a pea size is subjective, but an average mature pea is about .75 cm3, or about .42 the mass of roughly 8g… or 3.36g. I used 3g. whether it was 2g or 4g doesn’t make much difference. The idea was to see if a 1 ft wide crater was possible.
#50, KD… An object entering the atmosphere at 30,000-150,000 mph might not slow down to terminal velocity before it hits the earth. Dropping a marble from a tall building is not comparable. Giving it an initial velocity of say 3,000 or 4,000 mph would be.
Also, go to the link I provided. I calculated force of impact as outlined there (about half way down the page are the formulas)
Patrick, you just don’t get it. The meteorite is not being greatly accelerated. It is traveling at a near constant velocity, being somewhat decelerated by the atmosphere. It’s KE released on impact that determines the damage done, not force.
Give up. You lose.