Physics for
engineers
DOrSU guest lecture
Exercise 2123
Lecture
Week 8
Bastian
#21 Survive in artic waters
Without special insulation swimsuits, you cannot survive
for long if you dropped into cold water. If your body
temperature drops from 37°C down to 30°C, you become
unconscious. Calculate the energy loss of your body
corresponding to this temperature difference.
A human body can produce about 100 W of waste heat.
Calculate the thickness of a polyurethane insulation such
that you can maintain your body temperature.
#22 Global warming
The Earth is absorbing solar radiation. Calculate the radiation power that strikes (one half) of
the planet per area. As a consequence, the Earth heats up acting as a thermal radiation source
by itself. At which temperature does the incoming radiation compensate the outgoing radiation
intensity?
Earth on a surface
segment of a sphere
sun
earth
Radius 1.496∙1011 m