Question

When people exercise, they report feeling exhaustion when their body temp rises to 39.7 C a 68 kg man is running at 15 km/h on a hot muggy day that he cant lose any heat to the environment his body temp starts at 37 Chow long can he run til he feels exhaustion

Answer 1

Answer:

111 seconds

Explanation:

From research, it takes 4200 J to raise 1 kg of body temperature. Which means that specific heat capacity of human body with is; c = 4200 J/Kg°C

We are told that the temperature starts at 37°C and rises to 39.7°C

Thus: Δt = 39.7 - 37 = 2.7°C

Amount of energy required is given by the formula;

q = mcΔt

We are given m = 68 kg

Thus;

q = 68 × 4200 × 2.7

q = 77112 J

From research, the human body is 25% efficient.

Formula for power with velocity is;

P = F × V

F = mg = 68 × 9.81

V = 15km/h = 4.167 m/s

P = 68 × 9.81 × 4.167

P = 2779.72 W

Since the human body is 25%

Then the power of the utilized is;

25/100 × 2779.72 = 694.93 W

Now, we now that;

Power = work done/time taken

694.93 = 77112/t

t = 77112/694.93

t = 111 seconds.

Thus, it will take home 111 seconds to feel exhausted