Liquid helium has a very low boiling point, 4.2
K, as well as a low latent heat of vaporization,
2.09 x 104 J/kg. If energy is transferred to a
container of liquid helium at the boiling point
from an immersed electric heater at a rate of
10.0 W, how long does it take to boil away
2.00 kg of the liquid?