What is the sound? and tell his main types

Astronomers discover an exoplanet (a planet of a star other than the sun) that has an orbital period of 3.87 earth years in its circular orbit around its sun, which is a star with a measured mass of 3.59 x 1030 kg. find the radius of the exoplanet's orbit.

What are similarities and differences of reflection, refraction, diffraction and absorption?

The strong nuclear force acts over a small distance than the electrostatic force. true or false