skate 120 lb 0.10 in^2 1 atm 15 lb/in^2
It has been suggested that the pressure exerted on a skate blade
is sufficient to melt the ice beneath it and form a thin film of water,
which makes it easier for the blade to slide over the ice.
Assume that a skater weighs 120 lb and
the blade has an area of 0.10 in2.
Calculate the pressure exerted on the blade (1 atm = 15 lb/in2).
From information in the text,
calculate the decrease in melting point at this pressure.
Comment on the plausibility of this explanation and
suggest another mechanism by which the water film might be formed.
An increase in pressure of 134 atm is required
to lower the melting point of ice by 1℃.
---------------------------------------------------
Comment on the plausibility of this explanation and
suggest another mechanism by which the water film might be formed.
---> 이 부분은 필자도 모르므로,
녹는점 감소량만 계산해 보겠다.
From “1 atm = 15 lb/in2”,
---> 문제 지문에서 압력 계산 방법을 알려주었다.
P = lb / in2
= 120 lb / 0.10 in2
= 1200 lb/in2
1200 lb/in2 × (1 atm / 15 lb/in2)
= 80 atm
---> pressure applied on ice by skate blade
압력이 1 atm에서 80 atm으로 증가했으므로,
ΔP = 80 – 1 = 79 atm
얼음의 녹는점을 1℃ 감소시키는데
134 atm의 압력이 필요하므로,
79 atm × (1℃ / 134 atm) = 0.59℃
---> 녹는점 감소량
Thus, the decrease in melting point is
0.59℃
답: 0.59℃
[키워드] The pressure required to decrease the melting point of ice by 1℃ is 134 atm
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