Hubble’s law states that the velocity of a galaxy is equal to H0d. Substitute this value into the time equation, and simplify the equation. Use H to represent the Hubble constant.

Aray of light traveling parallel to the principal axis of a concave mirror will be reflected through the mirror's

Samir watches a 100-minute movie on his spaceship. maria's spaceshipe flies in the same direction as samir's spaceship but she observes his move to last 125 minutes and his spaceship to be 40 m long. how long does samir observe his own spaceship to be? according to an observer on earth, planet x is stationary. maria and samir depart earth on their spaceships at the same time, each flying at 0.5c. maria flies toward planet x and samir flies in the opposite direction. according to maria, her voyage to planet x takes 9 years. how many years does marias voyage take according to samir?

Achlorine atom has 17 protons and 18 neutrons. what is its mass number? what is its atomic number?