Which gives you a frame of reference for your speed when you are riding a train?

the wheels of the train

the sky overhead

the train track

the station

Lightning is an example of what phenomenon? a release of a large amount of energy an absorption of a large amount of energy a natural electric circuit a natural electric current

Two identical stars with mass m orbit around their center of mass. each orbit is circular and has radius r, so that the two stars are always on opposite sides of the circle. (a) find the gravitational force of one star on the other. (b) find the orbital speed of each star and the period of the orbit. (c) how much energy would be required to separate the two stars to infinity?

Awave with a frequency of 500 hz is traveling at a speed of 100 m/s.what is the wavelength?