07prob

# 07prob - Physics 9B-C Assignment#7 Cole[Q17.8 No you can do...

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Physics 9B-C Assignment #7 Cole [Q17.8] No, you can do work by changing the volume--compressing a gas is one way to change the temperature. Another is to do work against friction--rub your hands together. Likewise, if adding heat goes entirely into doing work, the temperature will not change. [Q17.25] The dark soil will heat very quickly and heat the air layer next to the ground. This hot layer is less dense than the air above it forming an unstable situation. Convection currents will develop in which there will be regions of quickly rising air which will carry the glider higher. [17.5] a) From Eq. (15-1), (9°F/5°C)(40.2°C) + 32° F = 104.4° F, which is cause for worry. b) (9°F/5°C)(12°C) + 32°F = 53.6°F, or 54°F [17.53] The kinetic energy which is converted to heat must raise the temperature to the melting point and then melt the bullet õ 1 2 2 mv mc mL =+ ∆Τ õ v cT L () = ° 22 130 327 3 24 5 10 3 J/kg·K C - 25°C J/kg .. = 357 m/s. [17.70] a) Hk A T x cc == × 385 100 1 W/m K 4 10 m °C - 65°C m -4 2 = 5.39 W. b) If energy is to be conserved, the heat fluxes through both rods must be equal ( energy cannot be created or destroyed any where in the rod. H c = H s õ k Ak A C L cs 100 1 65 0 2 m = ° õ L k k s c 2 65 35 = ° ° = 0.242 m. [17.91] a) d s = d õ dø s (1 + å s (T - Tø)) = d õ T dd d T C s ss = += × β α o o o 0 002 25 20 . /. in 1.2 10 in -5 = 87°C. b) Now both change their length: d s = d õ dø s (1 + å s (T - Tø)) = dø (1 + å (T - Tø)) õ Î T = s o o o o = × × ββ

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07prob - Physics 9B-C Assignment#7 Cole[Q17.8 No you can do...

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