An ingot of gold has dimensions of 10x5x5 cm. How much energy will be released when it is cooled from 90 ° C to 30 ° C?
| May 3, 2021 | education
a = 10 cm = 0.1 m.
b = 5 cm = 0.05 m.
h = 5 cm = 0.05 m.
t1 = 90 ° C.
t2 = 30 ° C.
C = 130 J / kg * ° C.
ρ = 19300 kg / m ^ 3.
Q -?
The amount of heat that is released is determined by the formula: Q = C * m * (t1 – t2).
We express the mass of the bar m by the formula: m = ρ * V.
The ingot has the shape of a rectangular parallelepiped, so its volume V is found by the formula: V = a * b * h.
Q = С * a * b * h * ρ * (t1 – t2).
Q = 130 J / kg * ° C * 0.1 m * 0.05 m * 0.05 m * 19300 kg / m ^ 3 * (90 ° C – 30 ° C) = 37635 J.
Answer: when the ingot cools down, Q = 37635 J of thermal energy is released.
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