## What is momentum?

Momentum is a central concept in both classical and modern physics. It tells us something about the force that a massive body–or massless particle–exerts in a collision. But how are the classical and quantum formulas related? What exactly is momentum? A textbook description of momentum merely characterizes the classical formula . The formula gives a … Read more

## What is Planck’s constant?

Planck’s constant is the famous constant of proportionality discovered by Max Planck at the end of the 19th century. The constant is instrumental in calculating physical quantities on tiny scales including the properties of elementary particles. Calculating a particle’s wavelength, momentum, and energy is simple. Multiply Planck’s constant by the right inputs and out comes … Read more

## What is the gravitational constant?

The gravitational constant is a number. What sets it apart from other numbers is that you can multiply the gravitational constant by the mass and radius of a large body to find the strength of its gravitational field. Calculating acceleration, force, energy, and other gravitational potentials is simple. Just multiply the constant by the right … Read more