The marker posts on a highway are 0.1 miles apart. If a truck is timed taking 5 seconds between posts, how fast is the truck going (in MPH; there are 3600 seconds in an hour)?

The two stars in a certain binary star system move in circular orbits. the first star, alpha, has an orbital speed of 36 km/s. the second star, beta, has an orbital speed of 12 km/s. the orbital period is 137 d. a) what is the mass of the star alpha? b) what is the mass of the star beta?

What are the similarities & differences between a thermistor and a light dependent resistor in physics?

In a classical model of the hydrogen atom, the electron moves around the proton in a circular orbit of radius 0.053 nm. what is the electron's orbital frequency? what is the effective current of the electron?