When you walk down a steep hill, the pressure on your knees is equal to three times your body weight.
199
Airports that are at higher altitudes require a longer airstrip due to lower air density.
39
Nearly 50% of the world's scientists are assigned to military projects.
71
The bark of an older redwood tree is fireproof.
65
In zero gravity, a candle's flame is round and blue.
16
A ball of glass will bounce higher than a ball made of rubber.
73