The Stefan-Boltzmann law states that the total radiant heat power emitted from a surface is proportional to the fourth power of its absolute temperature.
where E is the power from a unit area, T is the absolute temperature and the Greek letter sigma (σ) representing the constant of proportionality, called the Stefan-Boltzmann constant. In SI units, this constant has the value .
The law applies only to blackbodies, theoretical surfaces that absorb all incident heat radiation.
"From 10AM to 4PM are the most dangerous hours for exposure to the sun."
The first two don't make any sense. As for SPF, the FDA minimum is 15 but the recommended minimum is 30. 10AM-4PM are the peak sunlight hours, generally (unless you live in Antarctica of course).
Progressively Overloading his muscles, assuming he is doing weight training, to increase strength over time. he should not stay with the same weight for two months, unless he can perform more reps with better form over time.
