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What types of materials have low specific heats? What are some advantages/disadvantages to this?

What types of materials have low specific heats? What are some advantages/disadvantages to this? What types of materials or substances have high specific heats? What are some advantages/disadvantages to this?.

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What types of materials have low specific heats? What are some advantages/disadvantages to this?

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  1. What types of materials have low specific heats? What are some advantages/disadvantages to this? • What types of materials or substances have high specific heats? What are some advantages/disadvantages to this?

  2. Heat Examples Heat up Water from 21C to 95Cm = 1 kg c = 4186Q = mcDTQ = (1)(4186)(95 – 21)Q = 309,764 Joules

  3. Thermal Equilibrium • Two objects at different temperatures will eventually reach a common temp Tf? • Heat Gained = Heat Given • mcDT = mcDT • Example Soup (m = 1 kg, c = 4186, T=95) Mixed with a bowl (m=.8kg, c=800, T=20) (1)(4186)(95-T) = (.8)(800)(T-20) 397670 – 4186T = 640T – 12800 410470 = 4826T T = 85 0C

  4. Linear Expansion • All objects expand with increase in temperature, contract with decrease in temperature. • DL= L0aDT L0 is original length at original temperature, a is the expansion coefficient, and DT is the change in temperature. You are solving for the change in length.

  5. Latent Heat = the heat required to change the state of the object (liquid to gas, solid to liquid) • Lf = 3.35 E 5 J/kg (to melt ice, freeze water) • Lv = 2.26 E 6 J/kg (to make steam, condense water) • Q = mL • Water at densest point at 4 0C

  6. Problem Solving Hints • If ice is below 0, use mcDT and the c for ice, to warm ice. • At 0 the ice melts, use mLf • Between 0 and 100, it is water, use mcDT and the c for water, to warm water. • At 100 the water converts to steam, use mLv. • Above 100, use mcDT and the c for steam.

  7. Reading Quiz • Why does a tile floor feel colder than carpet on your bare feet? • Why does the temperature of melting ice not change even though energy is being added as heat to the ice?

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