Body Temperature, Energy and Heat Loss
Why does perspiring cause heat energy to be lost from the body? Because:
Being at a lower temperature than the skin, sweat cools skin by conduction.
Evaporating water molecules remove heat in the form of their own kinetic energy.
The presence of sweat on the skin prevents infrared radiation being absorbed.
Sweat on the skin allows heat to be lost to the air by conduction.
Evaporating water molecules remove heat in the form of their own kinetic energy.
Vaporising water molecules carry away more than the average kinetic energy. Temperature of an object is the average kinetic energy of its particles. The skin surface is left at a lower temperature.
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The Systรจme International (Standard International) unit of power is the watt. This unit is the same as which one of the following?A. Electronvolt
B. Joule
C. Joule per second
D. Kilojoule
Which of the following correctly states the principle of conservation of energy in terms of the human body? (Assume no foodstuffs are consumed and no urine or faeces are excreted.)
A. Q = s ร m ร ฮT (Q = energy, s = specific heat of tissue, m = body mass, T = body temperature)
B. The energy stored in the human body is equal to the energy lost from the body plus the work done by the body.
C. The energy value of the food we eat must exceed the energy value of the muscular activity we perform.
D. The change in the energy stored in the body is equal to the heat lost from the body plus the work done by the body.
On a normal winter day, by what means does the human body lose most of its heat?
A. Convection
B. Conduction
C. Radiation
D. Evaporation
Which one of the following statements does NOT accurately describe energy?
A. Energy can be created but not destroyed.
B. The total amount of all types of energy remains constant.
C. The energy gained by an object is the amount of work done on the object.
D. Energy is the heat given out when oxidation occurs.
Which choice explains how the evaporation of sweat “cools” our body?
A. Evaporating water molecules carry with them more than the average amount of kinetic energy which leaves the remaining molecules with a lower average kinetic energy.
B. The body loses more heat through the infrared radiation emitted by sweat than it gains from the infrared radiation emitted by the surroundings.
C. Sweat is at a lower temperature than our core body temperature so sweat on our skin cools us by conduction.
D. The water molecules in sweat are at a higher temperature than our core body temperature so losing sweat leaves us cooler due to the mass of water lost.
In which situation will the evaporation of sweat from the skin be ineffective as a heat loss method?
A. The air temperature is greater than human body temperature.
B. The air temperature is less than human body temperature.
C. The surrounding air is saturated with water vapour.
D. The human body is immersed in the water of a swimming pool.
What is the most effective way to deposit heat in bones and joints?
A. Ultrasound
B. Infrared radiation
C. Conductive heating (heat packs)
D. Diathermy
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