What condition is necessary for heat to flow between two objects?

What is the heat energy generated/emitted by the metal when a 250 kg lump of iron cools from 650° C to 20° C? Specific heat of iron is 449 J/kgC.

The first law of thermodynamics, the internal energy of a system can either be increased by adding heat or doing work on the system, is a restatement of the ____.

A student is investigating the best method for heating marshmallow using an open flame. The student quickly discovers placing the marshmallow over the flame is more effective than heating the marshmallow on the side of the flame.

According to this information, what type of heat transfer is present when the marshmallow is above the fire that is not present when the marshmallow is on the side of the fire?

NASA developed a reflective foil barrier to help shield spacecraft from heat transfer in space. These reflective barriers are not used in homes to prevent heat transfer by the same method. What method of heat transfer is being prevented by the reflective barrier?

What is the heat gained or lost when 20 kg of water experiences a change in temperature from 10° C to 40° C ? (Specific heat of water is 4186 J/kgC)

A​ tray filled with ice is removed from the freezer. After a short period of time, the ice begins to melt. As the ice melts, it ―

A student that just received their driver’s license decides to buy a new car. He remembers from physics class that heat engines have a thermal efficiency that can be calculated. He asks the car deal for a car that has a high thermal efficiency rating. The car dealer says he has a car that is 100% efficient.

Which law of thermodynamics best describes why the car cannot be 100% efficient?

A student is preparing to take a bath when she realizes that the hot water tap in the bathroom is not working. The student goes to the kitchen and prepares 20L of 100o​​C water to mix with 80L of 20o​​C . What will be the final temperature of the bath water?

How much heat is lost when a 64 g piece of copper cools from 375o​​C, to 26o​​C? (The specific heat of copper is 0.38452 J/g xo​​C)

If 100 grams of water is to be heated from 24.0°C to 100.0°C to make a cup of tea, how much heat must be absorbed? The specific heat of water is 4.184 J/g·°C

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In the lab, a student places a 5 kg container of water on a hot plate. The heating of the water is constant. The student records the temperature and graphs it as a function of time on the graph in the picture shown.

Which point on the graph has the lowest entropy level?

When it burns, a candle heats 45 grams of water from 21 to 28 C. How much energy did the candle give off? Specific heat of water is 4.184 J/gC

100.0 mL of 4.0°C water is heated until its temperature is 37°C. If the specific heat of water is 4.184 J/g°C, calculate the amount of heat energy needed to cause this rise in temperature.