Exam 14: Heat

A 100 gram glass container contains 200 grams of water at 10 °C. A 200 gram piece of lead at 150 °C is added to the water in the container. What is the final temperature of the system? (specific heat of water = 4,186 J/kg °C, specific heat of glass = 837.2 J/kg °C, specific heat of lead = 127.7 J/kg °C)

A 100 g glass container contains 250 g of water at 15.0 °C. A 20.0 g piece of lead at 100 °C is added to the water in the container. What is the final temperature of the system in °C? (specific heat of water = 1.00 cal/g °C, specific heat of glass = 0.200 cal/g °C, specific heat of lead = 0.0310 cal/g °C)

A brass rod with a length of 20.0 cm is placed end to end with an aluminum rod with a length of 20.0 cm, and this system is placed between a hot temperature of 100 °C and a cold temperature of 10.0 °C. The thermal conductivities of the brass and the aluminum are 100 W/m °C and 230 W/m °C, respectively. The rods have the same cross-sectional area of 25.0 cm². What is the heat flow from the hot temperature to the cold temperature?

The heat of fusion for gold at 1,063 °C is 66.6 kJ/kg and the specific heat of gold is 0.128 kJ/kg °C. What is the energy needed to melt 100 grams of gold starting at 0 °C?

What type of heat transfer is used to carry heat from the house furnace to the living room of most houses?

A 50.0 g glass container contains 200 g of water at 20.0 °C. A 20.0 g piece of an alloy at 100 °C is added to the water in the container. The final temperature of the mixture is 24 °C. What is the specific heat of the alloy in cal/g °C? (specific heat of water = 1.00 cal/g °C, specific heat of glass = 0.200 cal/g °C)

A brass rod is placed between two temperature sources so that heat can flow between them. One temperature is 80 °C and the other temperature is 20 °C. The length of the rod is 50.0 cm and the cross-sectional area is 15.0 cm². If the thermal conductivity for brass is 100 W/m °C, then what is the heat flow between the hot temperature and the cold temperature?

Imagine a space heater consisting of an iron ball (radius 10.0 cm) through which electrical current is passed in order to heat the ball. What temperature would it need to be in order to radiate a net power of 500 W into the surrounding air (which is at a temperature of 20 °C)? Assume the ball is a perfect blackbody.

A 2,000 kg car is traveling at 15.0 m/s down a long mountain grade of 2.00%. The mountain road is 5.0 km long. The heat generated at the brakes due to friction heats up the brakes. The mass of the brake system is 20.0 kg and it has a specific heat of 0.200 kcal/kg °C. What is the increase in the temperature of the brakes?

A person of mass 90.0 kg walks up a flight of stairs that are 12.0 meters high. What is the required energy of the exercise in Calories?

Radiant energy from the Sun reaches the Earth at a rate of 1.70 × 10¹⁷ W. When 30.0% of the radiant energy is reflected and 70.0% absorbed, the average temperature of the Earth's atmosphere is 253 K or −20 °C. If the atmosphere reflected 20.0% and absorbed 80.0% of the solar radiant energy, then what would be the average temperature of the Earth's atmosphere?

The specific heat of ice is 2.10 kJ/kg °C, the heat of fusion for ice at 0 °C is 333.7 kJ/kg, the specific heat of water 4.186 kJ/kg °C, and the heat of vaporization of water at 100 °C is 2,256 kJ/kg. What is the final equilibrium temperature when 10.0 grams of ice at −15 °C is mixed with 40.0 grams of water at 75 °C?

A tungsten light bulb is glowing with blackbody radiation whose maximum occurs at a wavelength of 700.0 nm. What is the temperature of the tungsten element?

The specific heat of ice is 2.10 kJ/kg °C, the heat of fusion for ice at 0 °C is 333.7 kJ/kg, the specific heat of water 4.186 kJ/kg °C, the heat of vaporization of water at 100 °C is 2,256 kJ/kg, and the specific heat of steam is 2.020 kJ/kg °C. What is the final equilibrium temperature when 30.0 grams of ice at 0 °C is mixed with 4.00 grams of steam at 120 °C?

What is the heat needed to heat 150 g of water from 10.0 °C to 100 °C? (specific heat of water = 4,186 J/kg °C)

The specific heat of water is 1.000 cal/(g·°C). What is the specific heat of water in SI units?

A Styrofoam cooler has a surface area of 2,700 cm² and a wall thickness of 3.00 cm. Styrofoam has a thermal conductivity of 0.010 W/m °C. A 2.00 kg block of ice is placed inside the cooler that has a temperature inside of 2°C. When the temperature outside is 30.0°C, the ice lasts for 8.00 hours. If the temperature outside becomes 20.0°C, then how long will the ice last? Ignore the effect of the air inside the cooler.

A student is sleeping under a small goose-down comforter that has thermal conductivity of 0.025 W/m °C. The thickness of the down comforter is 5.0 cm and the area of the comforter is 2.0 m². If the temperature difference between inside of the comforter and the outside of the comforter 40 °C, then what is the rate of heat flow through the comforter?

A circular window in the wall of a home has a diameter of 25 cm and is made of a single pane of glass 0.30 cm thick. The thermal conductivity for the glass is 0.63 W/(m·K). What heat is lost through the window in 12 s if the temperature inside the house is 20 °C and outside is −12 °C?

A 2,000 kg car is traveling at 20.0 m/s down a long mountain grade of 1.00%. The mountain road is 3.00 km long. The heat generated at the brakes due to friction heats up the brakes. The mass of the brake system is 20.0 kg and it has a specific heat of 0.200 kcal/kg °C. What is the increase in the temperature of the brakes?