Help please Luminosity is the amount of energy emitted by a star each second. Stars radiate light over a broad range of frequencies in the electromagnetic spectrum, from the low energy radio waves to high energy gamma rays. The luminosity of a star depends on two factors:
A)age and surface area.
B)surface area and temperature.
C)gravity and distance from Earth.
D)distance from Earth and temperature.

the answer is c) an oak tree

before, trains worked using the steam engine. thus, it uses heat so it is crucial to apply heat balance. the steam engine absorbs energy during the stage of boiling water. so, this is the endothermic reaction. when the steam is used to work the piston, it has to release this energy through running the train. the excess energy is released as an exhaust to the chimney. this is the exothermic process because it releases energy to the surroundings.

sound moves fastest in solids because the molecules are tightly packed and it allows sound to vibrate