Which response is represented by the symbol ccal

Note that Example 2 is an illustration of the mechanical equivalent of heat. Alternatively, the temperature increase could be produced by a blow torch instead of mechanically. Suppose you pour 0. Assume that the pan is placed on an insulated pad and that a negligible amount of water boils off.

What is the temperature when the water and pan reach thermal equilibrium a short time later? The pan is placed on an insulated pad so that little heat transfer occurs with the surroundings.

Originally the pan and water are not in thermal equilibrium: the pan is at a higher temperature than the water. Heat transfer then restores thermal equilibrium once the water and pan are in contact. Because heat transfer between the pan and water takes place rapidly, the mass of evaporated water is negligible and the magnitude of the heat lost by the pan is equal to the heat gained by the water.

The exchange of heat stops once a thermal equilibrium between the pan and the water is achieved. Bring all terms involving T f on the left hand side and all other terms on the right hand side. Solve for T f ,. This is a typical calorimetry problem—two bodies at different temperatures are brought in contact with each other and exchange heat until a common temperature is reached.

Why is the final temperature so much closer to The reason is that water has a greater specific heat than most common substances and thus undergoes a small temperature change for a given heat transfer. A large body of water, such as a lake, requires a large amount of heat to increase its temperature appreciably. This explains why the temperature of a lake stays relatively constant during a day even when the temperature change of the air is large.

However, the water temperature does change over longer times e. Which sample cools off the fastest? This activity replicates the phenomena responsible for land breezes and sea breezes. The heat transfer depends only on the temperature difference. Since the temperature differences are the same in both cases, the same 25 kJ is necessary in the second case.

Figure 3. Radioactive spent-fuel pool at a nuclear power plant. Spent fuel stays hot for a long time. Department of Energy. Skip to main content. Heat and Heat Transfer Methods. Search for:. Temperature Change and Heat Capacity Learning Objectives By the end of this section, you will be able to: Observe heat transfer and change in temperature and mass.

Calculate final temperature after heat transfer between two objects. Example 1. Strategy The pan and the water are always at the same temperature. Solution Because water is in thermal contact with the aluminum, the pan and the water are at the same temperature. Calculate the heat transferred to the water.

Calculate the heat transferred to the aluminum. Discussion In this example, the heat transferred to the container is a significant fraction of the total transferred heat. Example 2. Example 3. Strategy The pan is placed on an insulated pad so that little heat transfer occurs with the surroundings.

To study differences in heat capacity: Place equal masses of dry sand or soil and water at the same temperature into two small jars. The average density of soil or sand is about 1. Heat both using an oven or a heat lamp for the same amount of time. Record the final temperature of the two masses. Now bring both jars to the same temperature by heating for a longer period of time. Remove the jars from the heat source and measure their temperature every 5 minutes for about 30 minutes.

Solution The heat transfer depends only on the temperature difference. You may assume the car to stop sufficiently fast so that no heat transfers out of the brakes. What is the net heat transfer during this heating? Ignore any complications, such as loss of water by evaporation. To sterilize a How much heat transfer is required? The same heat transfer into identical masses of different substances produces different temperature changes. Calculate the final temperature when 1.

Rubbing your hands together warms them by converting work into thermal energy. If a woman rubs her hands back and forth for a total of 20 rubs, at a distance of 7. Because of its much larger mass, the swimming pool of water has a larger heat capacity than the bucket of water. Different substances respond to heat in different ways. If a metal chair sits in the bright sun on a hot day, it may become quite hot to the touch. An equal mass of water in the same sun will not become nearly as hot.

Water is very resistant to changes in temperature, while metals in general are not. Table below lists the specific heats of some common substances. The symbol for specific heat is c p , with the p subscript referring to the fact that specific heats are measured at constant pressure. Notice that water has a very high specific heat compared to most other substances. Water is commonly used as a coolant for machinery because it is able to absorb large quantities of heat see Table above.

Coastal climates are much more moderate than inland climates because of the presence of the ocean. Water in lakes or oceans absorbs heat from the air on hot days and releases it back into the air on cool days. This power plant in West Virginia, like many others, is located next to a large lake so that the water from the lake can be used as a coolant.