What is efficiencywhat is the formula of mechanical advantage and velocity ratio of labour

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?

Thermal radiation gets its name because

Ascience teacher heated liquid ethanol for an experiment. when he turned up the temperature, the ethanol quickly disappeared, and a strong aroma filled the room. what happened to the ethanol?