Water is completely filling black metallic vessel having cubic form and thin walls. The mass of water is 1 kg and initial temper
ature 50 C. This cubic vessel is placed into black cavity whose walls are kept at the constant temperature of 0 C. Find time t it takes for the water to cool down to 10 C. Water specific heat is 4200 (J/kg K-1 .) After you find an answer, estimate whether this radiation mechanism would be responsible for the real-life water cooling and what other mechanisms might be in play.
1 answer:
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Answer:
a) t = 1.47 h b) t = 1.32 h
Explanation:
a) In this problem the plane and the wind are in the same North-South direction, whereby the vector sum is reduced to the scalar sum (ordinary). Let's calculate the total speed
v = f -
v = 585 -32.1
v = 552.9 km / h
We use the speed ratio in uniform motion
v = x / t
t = x / v
t = 815 /552.9
t = 1.47 h
b) We repeat the calculation, but this time the wind is going in the direction of the plane
v= f -
v 585 + 32.1
v = 617.1 km / h
t = 815 /617.1
t = 1.32 h