Saturday, December 31, 2005
How to break Silly Putty
From Boing Boing Dec 30
How to break Silly Putty
A couple of days ago someone wrote about a Google employee who mashed together 250 lbs of Silly Putty and then had a hard time breaking it up into chunks. Today Dr. Paul J. Camp, from the Department of Physics at Spelman College in Atlanta, GA emailed to say:"I guess they didn't try smacking it with a hammer.
"Silly Putty is a bizarre polymer, but like most polymers it has a transition temperature at which its physical properties change. In this case, there is a glass transition temperature (Tg) -- below Tg, the polymer will behave like a glass and shatter on impact instead of deforming. For example, PVC has a Tg of 83 C which makes it a reasonable choice for cold water pipes but not for hot water, which would cause it to flow like Silly Putty (addition of various plasticizers can adjust the Tg). However, often the viscoelastic properties of polymers have a rate dependence and this is the case for Silly Putty. Do the same amount of work over a much shorter time (smack it with a hammer instead of pulling) and the SP behaves as if its Tg has been raised. It then shatters into bits.
"You can read a mildly confusing scientific explanation here (from Case Western) along with pictures of Silly Putty subjected to the same force at different rates, or if you prefer a more visceral experience, watch the video from this experiment of what happens when you drop a 50 pound beach ball made of Silly Putty off the roof of a building."
BERLIN (Reuters) - German police Thursday captured two men suspected of stealing from 15 cars and two garden sheds by following their footprints in the snow for several miles.
Policemen were checking up on a car whose alarm had been set off just after midnight in the town of Hoentrop when they found a smashed window and two sets of footprints which they followed more than ten streets.
"At one point the tracks disappeared because someone had cleared the pavement outside their home in the middle of the night," police said in a statement.
After this minor setback, the officers picked up the trail again. The two sets of footprints led them directly to the entrance of a flat where the burglars not only stored their booty but also left their shoes and gloves to dry.
Wednesday, December 07, 2005
Theodore Roosevelt's ideas on Immigrants and being an AMERICAN in 1907.
"In the first place, we should insist that if the immigrant who comes here in good faith becomes an American and assimilates himself to us, he shall be treated on an exact equality with everyone else, for it is an outrage to discriminate against any such man because of creed, or birthplace, or origin. But this is predicated upon the person's becoming in every facet an American, and nothing but an American...There can be no divided allegiance here. Any man who says he is an American, but something else also, isn't an American at all. We have room for but one flag, the American flag... We have room for but one language here, and that is the English language... and we have room for but one sole loyalty and that is a loyalty to the American people."
Theodore Roosevelt 1907
Army wants you
man, was drafted by the US Army. On his first day in
basic training the army issued him a comb. That
afternoon the Army barber sheared off all his hair.
On his second day the Army issued Herman a toothbrush.
That afternoon the Army dentist removed seven of his teeth.
On the third day the Army issued him a jock strap.
Friday, December 02, 2005