12.4 A 1.32 kg sample of some material increases in temperature from 13.5°C to 39.2°C when 1.98×10^4 J of heat energy is
transferred to it. What is the specific heat of the material?
J/kg·K
12.5 A 2.4 kg iron ball is dropped from a height of 14 m onto a concrete roadway, and 2.5% of its kinetic energy at the time it
reaches the ground is transformed into internal energy in the ball itself. (The rest of the energy is transmitted to the ground,
converted into sound energy, and so on.) What is the ball's increase in temperature?K
12.6 A 0.00340 kg lead bullet is traveling at 473 m/s when it hits the bull's-eye of a practice target. Half of the bullet's kinetic
energy is transferred to the bullet in the form of heat. What is the resulting temperature increase in the bullet? Assume that
the specific heat of the lead does not vary significantly over this temperature.
K
12.7 A lead block and a silver block are both at the temperature of 41°C. They then each absorb the same amount of heat, and,
without any exchange of heat between them or with the environment, their new final temperatures are again the same. (a) If
the mass of the lead block is 5.0 kg, what is the mass of the silver block? (b) If they each absorbed 6.9×10^3 J, what is their
final temperature?
(a) kg
(b) °C
12.8 As a body of water gives up heat energy to the air above it, the air temperature increases. Assume 1.0 kg of water (about one
liter) decreases 1.0 K in temperature, giving up its energy to a nearby body of air. (a) What mass of air could the energy from
the water increase by 1.0 K in temperature? (b) Assume the density of the air is 1.2 kg/m^3. What is the volume of this mass of
air?(a) kg
(b) m^3
12.9 A samovar is a Russian urn, often made of silver, for serving tea. A large samovar made from 4.62 kg of silver is filled with
11.3 kg of tea, at the same temperature. How much heat is required to raise the temperature of both the samovar and tea by
34.7 C°? (Assume the specific heat of tea is the same as that of water, 4178 J/kg·K.)
JSection 13 - Sample problem: a calorimeter
13.1 A large handful of identical gemstones, totaling 195 carats (one carat has a mass of 200 mg) at temperature 73.2°C, is
placed in a calorimeter filled with 0.594 kg of water at 13.6°C. After thermal equilibrium is established, the water temperature
is 14.1°C. What is the specific heat of the gemstone material?
J/kg·K
13.2 An Italian chef, who is very scientific in her approach to cooking, measures the specific heat of a porcini mushroom by placing
it in a calorimeter filled with 0.678 kg of olive oil at 13.2°C. The mushroom has mass 0.0802 kg and temperature 24.3°C
before being placed into the calorimeter. The olive oil's temperature is 14.7°C after thermal equilibrium is reached. The
specific heat of olive oil is 1970 J/kg·K. What is the specific heat of the mushroom?
J/kg·KSection 15 - Latent heat
15.1 An ice cube with a mass of 0.0410 kg at 0°C melts to water with no change in temperature. How much heat does the ice
absorb while melting?
J
15.2
A large pot is placed on a stove and 1.2 kg of water at 14°C is added to the pot. The temperature of the water is raised evenly
to 100°C just before it starts to boil. (a) What amount of heat is absorbed by the water in reaching 100°C? (b) The water then
boils until all of it has evaporated, turning to water vapor at 100°C. How much heat does the water absorb in this process?
(a) J
(b) J
15.3 How much heat is required to change 1.83 kg of solid lead at 135°C to liquid lead at 327°C?
J(^358) Copyright 2007 Kinetic Books Co. Chapter 18 Problems