Why do things fall to the ground without magic? Find out in The Secrets of Gravity: In the footsteps of Albert Einstein. The twelve year old Luke is far more interested in the universe and its secrets ...

Newton's Law of Universal Gravitation is written as: \(F=G\frac{m_1m_2}{r^2}\) The constant of proportionality is the universal gravitational constant ("big G") which equals \(6.674\times{10^{- 11}} ...