To understand specific heat and latent heat and how they are related to temperature versus time graphs.

energy can be added to a system either by doing work w on it or by adding heat q to it. energy transfer by work requires a force to act through some distance. energy transfer in the form of heat occurs between objects that are at different temperatures, with energy spontaneously traveling from the higher-temperature object to the lower-temperature one. when energy is added to an isolated system in the form of heat, either the temperature t of the system will increase or the system will undergo a phase change at a fixed temperature.

the specific heat c of a sample characterizes the rate at which it changes temperature per unit mass when it receives energy in the form of heat. the relationship between the energy input in the form of heat q and the resulting temperature change ? t is

q=mc? t,

where m is the mass of the sample and c is its specific heat, which depends on its phase. for this problem, assume that specific heat values are a constant for all temperatures within a given phase, which is a good approximation.

the latent heat l of a sample characterizes how much energy is required per unit mass to force the system to undergo a phase change at a fixed temperature. the amount of energy input in the form of heat q required to completely change the phase of a sample with mass m is

q=ml.

phase changes between solid and liquid phases are characterized by a latent heat of fusion lf. phase changes between liquid and gas phases are characterized by a latent heat of vaporization lv.

in general, every phase (solid, liquid, or gas) has its own specific heat value and every phase change has its own latent heat value.

if the cooling power remains constant, what will be the temperature of the system tb after it has been in the freezer for exactly 1 hour? this temperature is off scale on the figure.

Jessie ran 5000 meters from the cops and an average speed of 6 meters / second before he got caught . how long did he run?

Asher cycles 12 miles in 16 hours. what is his speed?

Question 1 what is amperage? is the rate of doing work. is the rate of flow of protons in electric current. represents the amount of pressure behind electron flow. is the rate of flow of electrons in electric current. 2 points question 2 what is voltage? is the rate of doing power. represents the amount of pressure behind electron flow. is the rate of doing work. is the rate of flow of electrons in electric current. 2 points question 3 what is power? is the rate of flow of protons in electric current. is the rate of flow of electrons in electric current. is the rate of doing work. represents the amount of pressure behind electron flow. 2 points question 4 if we multiply volts times amps we get what? power circuit work current 2 points question 5 what are two ways alternating currents are similiar? in both ac and dc electrons flow in the same pattern. in both ac and dc, the flow of electrons changes directions back and forth. both ac and dc are only possible in certain materials with atoms that will allow electron flow. both ac and dc involve the flow of electrons. 4 points question 6 how does the flow of electrons flow in an alternating current? the flow of electrons is always slower in an alternating current than within a direct current. the flow of electrons is not constant and forward; it changes direction back and forth. electrons flow from from a higher affinity to that of a lower affinity. electron flow is constant and only in a forward direction. 2 points question 7 what is the flow like in a direct current? the flow of electrons is not constant and forward; it changes direction back and forth. the flow of electrons is constant and only in a forward direction. the flow of electrons go from a higher affinity to a lower affinity. the flow of electrons are always faster in a direct current. 2 points question 8 how is an electric current able to flow? electrons flow from the higher affinity to lower affinity and electrical current is generated. protons flow from the higher affinity to lower affinity and electrical current is generated. the movement of protons from one atom to another leads to an electric charge. the movement of electrons from one atom to another atom in a line results in a flow of electric current. 2 points question 9 how do electrons move from the two different types of metal in a battery? protons flow from the metal with the lower affinity to the metal with higher affinity and electrical current is generated. electrons flow from the metal with the lower affinity to the metal with higher affinity and electrical current is generated. electrons flow from the metal with the higher affinity to the metal with lower affinity and electrical current is generated. protons flow from the metal with the higher affinity to the metal with lower affinity and electrical current is generated.