**Pre-reqs:** None. I intend to talk about forces and force diagrams, but there is a more fundamental question to address first. What is a force? Most texts define it as a push or a pull. That really ...

Friction is a force that always opposes motion. Force is measured in newtons (N). A force is a push or a pull. Contact forces arise between two objects which are in contact. Non-contact forces act ...

It is true that gravity is weakest among the fundamental forces. However, the effect of gravity can be felt even at arbitrarily large distances for two reasons. The first is a consequence of the ...

At the end of the 18th century, the British scientist Henry Cavendish measured the force of gravity between two objects for the first time in a laboratory. The objects in question were lead balls, one ...

In any direction! The distance between the Earth and the Sun is a careful balance between the mass of the Earth, the mass of the Sun, the speed with which the Earth orbits the Sun, and the strength of ...