Suppose a human could live for two hours (120 minutes ) unclothes in a

[manal950]

Suppose a human could live for two hours (120 minutes ) unclothes in air at 45 F . How long could he live in water at 45 F ?

how do the thermal conductivities of water and air compare ?
Air : k = 0.0251 W/mC ,
water = k = 0.597 W/mC


my answer

now for conduction we will say that

-k(air ) .A(dT/dx) dtime = -k(water ) .A(dT/dx) dtw

= 0.025 X 2 / 0.597

= 0.083 second

 

[Borek]

= 0.025 X 2 / 0.597

= 0.083 second

Huh?

No idea what is what of what nor how you got the number you got.

What is 2?

And your math is incredibly off.

 

[manal950]

sorry

= 0.025 X 120 / 0.597

= 5.04

 

[Borek]

That looks much more palatable.

It won't hurt to include units in your answer.

 

[Nickie]

Based on the provided information, it is likely that a human could survive longer in water at 45 F compared to air at the same temperature. This is because the thermal conductivity of water is significantly higher than that of air, meaning that heat is transferred more efficiently in water. Therefore, the human's body temperature would decrease at a slower rate in water, allowing them to potentially survive for a longer period of time. However, this is only one factor to consider and other variables such as the person's body composition and overall health would also play a role in their survival time. It is also important to note that these calculations are based on ideal conditions and may vary in real life situations. Further research and experimentation would be needed to determine a more accurate answer.