An o-ring is a loop of elastomer with a round (o-shaped) cross-section used as a mechanical seal. Successful o-ring joint design requires a rigid mechanical mounting that applies a predictable deformation to the o-ring. This introduces a calculated mechanical stress at the o-ring contacting surfaces. As long as the pressure of the fluid being contained does not exceed the contact stress of the o-ring, leaking cannot occur. Why did the o-ring of the Space Shuttle Challenger fail?
Back in the day
A tsunami is a series of waves generated when a body of water is rapidly displaced on a massive scale. The deadliest tsunami in recorded history, the Indian Ocean tsunami, killed about 300,000 people. It was triggered by an earthquake in the Indian Ocean that registered between a 9.1 and a 9.3 on the Richter scale. The disaster prompted a huge worldwide effort to help victims of the tragedy. How far down the shores of the continent of Africa did the tsunami extend?
Born on a day like today
Chairman Mao proclaimed the People's Republic of China in 1949. His Great Leap Forward was an initially successful effort to establish a system of collective farms and small industry, but it eventually led to the starvation of millions of people. Mao also launched a massive purge to eliminate counterrevolutionary elements in the country's institutions. The movement led to the destruction of much of China's cultural heritage and the imprisonment of many Chinese intellectuals; what was it called?