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A Level Specific Heat Capacity Questions

 

Q8. A female runner of mass 60 kg generates thermal energy at a rate of 800W.

(a) Assuming that she loses no energy to the surroundings and that the average specific heat capacity of her body is 3900 J kg-1K-1, calculate

(i) the thermal energy generated in one minute,

(ii) the temperature rise of her body in one minute.

(3 marks)

(b) In practice it is desirable for a runner to maintain a constant temperature. This may be achieved partly by the evaporation of sweat. The runner in part (a) loses energy at a rate of 500W by this process. Calculate the mass of sweat evaporated in one minute.

(specific latent heat of vaporisation of water = 2.3 x 10 6 J kg-1)

(3 marks)

(c) Explain why, when she stops running, her temperature is likely to fall.

(2 marks)

(Total 8 marks)