Rubbing your hands together warms them by converting work into
thermal energy. If a woman rubs her hands back and forth for a
total of 10 rubs a distance of 7.50 cm each and with a frictional
force averaging 50.0 N, what is the temperature increase? The mass
of tissue warmed is only 0.100 kg, mostly in the palms and
fingers.
_________
The work done by the friction force is equal to the amount of
thermal energy which is transferred.
Work = Ff * Total distance in meters
7.50 cm = 0.075 m, Distance back and forth = 0.150 m
Total distance = 10 * 0.150 = 1.5 m
Work = 50 * 1.5 = 75 N * m
This is the amount of thermal energy which was transferred to the
tissue.
?Q = mass * Specific heat * ?T
You need to know the specific heat of the tissue.
According to the website below, the average specific heat of the
human body is 3470 J/(kg * ?C)
http://www.engineeringtoolbox.com/human-body-specific-heat-d_393.html
75 = 0.1 * 3470 * ?T
?T = 75
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