Producing electricity in power stations is not very efficient. in power station a, 800 joules of energy from coal produce 300 joules of electrical energy.

calculate the efficiency of this power station.

Which two particles are found in the center of an atom

The sun’s mass is 2.0×10^ 30 kg, its radius is 7.0×10 5 km, and it has a rotational period of approximately 28 days. if the sun should collapse into a white dwarf of radius 3.5×10 3 km, what would its period be if no mass were ejected and a sphere of uniform density can model the sun both before and after?

Frank just graduated from eighth grade. assuming exactly four years from now he will graduate from high school how many seconds does he have until his high school graduation