When you walk down a steep hill, the pressure on your knees is equal to three times your body weight.
199
During photosynthesis, plants emit light humans can’t see, but NASA can see that light from space - and they've even made maps of it!
21
At room temperature, the average air molecule travels at the speed of a rifle bullet.
55
Sound travels about 4 times faster in water than in air.
408
In Arizona, a solar wind energy tower has been proposed that would generate as much energy as the Hoover Dam.
5
The brain case [of Neanderthals] on the average was more than 13 percent larger than that of the average of modern man
61
For every gallon of sea water, you get more than a quarter pound of salt.
45
According to studies, men change their minds two to three times more often than women.
72