Engineering Fundamentals: An Introduction to Engineering, 4th ed.c

11.5 Some Temperature-Related Material Properties 333

Example 11.14 Calculate the change in length of a 1000-ft-long stainless steel cable when its temperature

changes by 100F.

We will use Equation (11.25) and Table 11.10 to solve this problem. From Table 11.10 the

coefficient of thermal expansion for stainless steel is a2.9 10

 6

1/F. Using Equation (11.25),

we have

Specific Heat

Have you noticed that some materials get hotter than others when exposed to the same amount of

thermal energy? For example, if we were to expose 1 kg of water and 1 kg of concrete to a heat source

that puts out 100 J every second, you would see that the concrete would experience a higher tem-

perature rise. The reason for this material behavior is that when compared to water, concrete has a

lower heat capacity. More explanation regarding our observation will be given in Example 11.16.

Specific heatprovides a quantitative way to show how much thermal energy is required to

raise the temperature of a 1 kg mass of a material by 1Celsius. Or, using U.S. Customary units,

the specific heat is defined as the amount of thermal energy required to raise the temperature of

a 1-lb mass of a material by 1Fahrenheit. The values of specific heat for various materials at

constant pressure are given in Table 11.11. For solids and liquids in the absence of any phase

¢LaLL ¢T 1 2.9 10

 6

1/°F 21 1000 ft 21 100°F 2 0.29 ft3.48 in.

TABLE 11.11 Specific Heat (at Constant Pressure) of Some Materials at 300 K

Material Specific Heat ( J/kgK)

Air (at atmospheric pressure) 1007

Aluminum (pure) 903

Aluminum alloy-2024-T6 (4.5% copper, 1.5 % Mg, 0.6% Mn) 875

Asphalt 920

Bronze (90% copper, 10% aluminum) 420

Brass (70% copper, 30% zinc) 380

Brick (fire clay) 960

Concrete 880

Copper (pure) 385

Glass 750

Gold 129

Iron (pure) 447

Stainless steels (AISI 302, 304, 316, 347) 480, 477, 468, 480

Lead 129

Paper 1340

Platinum (pure) 133

Sand 800

Silicon 712

Silver 235

Zinc 389

Water (liquid) 4180

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