A 110-kg steel support rod in a building has a length of 2.0 m at a temperature

Question

A 110-kg steel support rod in a building has a length of 2.0 m at a temperature of 20°C. The rod supports a hanging load of 2,000 kg.

(a) Find the work done on the rod as the temperature increases to 39°C. (Assume the average coefficient of linear expansion for steel is 11 106 (°C)1.)
J

(b) Find the energy Q added to the rod (assume the specific heat of steel is the same as that for iron, 448 J/(kg · °C) and enter your answer to at least six significant figures).
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(c) Find the change in internal energy of the rod. (Enter your answer to at least six significant figures).

Explanation / Answer

a) L = L0**T = 2.0m*1.1x10^-5*19 = 4.18x10^-4m

So W = F*d = 2000kg*9.8m/s^2*4.18x10^-4 = 8.1928 J

b) Q = m*c*T = 2000*448J/kg-oC*19oC = 17024000 J

c) U = Q - W = 1.7024 x10^7 - 8.1928 = 17023991.8 J

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