In a surface wave (such as a water wave), particles

What is the acceleration of a spaceship that is initially at rest and then speeds up to 220 m/s in 20 seconds

The difference between a red shift and a blue shift has to do with wavelength frequency. t or f

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?