High School Physics : Understanding Heat and Work
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Example Question #1 : Understanding Heat And Work
The formula for the net energy added to a system is;
The change in energy equals the heat energy minus the work done.
We don't know the work, but we can solve for it using the work equation:
We are given both the force and the distance, allowing us to calculate the work.
Now that we know both the work done and the heat added, we can solve for the final energy of the system.
Example Question #1 : Understanding Heat And Work
A certain amount of heat energy is added to a closed system. A few moments later, a scientist observes that the total increase in energy is LESS than that heat energy added to the system. Which could be a valid explanation for this conclusion?
The system is not actually closed
Work was done by the system
External forces are acting upon the system
The measuring tools were incorrectly calibrated
The system is imperfectly designed
Work was done by the system
The most likely explanation is that work is done by the system.
The formula for change in energy shows that the net change in energy is equal to the increase in heat energy minus the work done:
Since 
Example Question #2 : Understanding Heat And Work
A bathtub and a coffee cup both contain water at 
The cup contains more heat, and the two have the same temperature
The two contain the same amount of heat, and the bathtub has a higher temperature
The bathtub contains more heat, and the two have the same temperature
The two contain the same amount of heat and have the same temperature
The bathtub contains more heat, and the two have the same temperature
Heat is a form of energy, while temperature is a measure of the average kinetic energy of the molecules present in a system. Since both systems are measure to be at 
Example Question #3 : Understanding Heat And Work
In order for heat transfer to occur, which of the following must be present?
Air
Temperature gradient
Interface between two mediums
All of these must be present for heat transfer to occur
Temperature gradient
A temperature gradient is always needed for heat transfer to occur. The temperature difference is what drives a flow of heat, as heat will always travel from an area of higher temperature to an area of lower temperature. This can occur between two materials, or within a single material. For example, if an iron pot is placed on a stovetop, the entire metal pot will become hot even though only the bottom is in contact with the heat source. This is because the heat transfers through the metal, from the high heat at the bottom to the lower heat at the top.
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