Physical Science 103



Physical Science 103Summer, 2017Exam #2 ReviewOBJECTIVESHeat and Heat TransferCompare the properties of substances with high and low specific heat capacities.Conduct an experiment to explain how specific heat capacity influences the change in temperature of a pare the mathematical proportionality of mass, temperature change, specific heat, and heat.Conduct an experiment to determine the specific heat of an unknown substance.Explain temperature in terms of the kinetic energy of the particles of a substance.Explain how energy is transferred via conduction, convection and radiation.Explain the effect of temperature on the volume, pressure, and density of a substance.Explain why the color black is a better absorber of radiant energy than white.Explain the effect of temperature on the pressure exerted by a gas.Distinguish between a thermal conductor and an insulator.Convert between the units joules, calories, and Calories.ElectricityDescribe the motion of electrons from negative towards the positive terminal when using a battery.Recognize and apply the concepts of current, voltage and resistance in a series and parallel circuit.Using Ohm’s Law and the equation for electrical power, apply and calculate for each of the variables and use their units appropriately.Identify basic electrical components (battery, wire, bulbs) in terms of schematic diagrams. Draw and interpret schematic diagrams of simple and compound bine cells in parallel and in series and know how these combinations affect voltage in a bine light bulbs in series and in parallel and be able to predict how these combinations affect the current and voltage in the circuit.Predict how undoing a light bulb in a parallel or series circuit affects the current, voltage, and resistance in the other parts of the circuit.Differentiate between D.C. and A.C. current.Show that kilowatt-hour is a unit of energy and be able to calculate the number of kilowatt-hours used by an electrical device and its cost if one knows its voltage, current, time of use and the cost per kilowatt-hr.The specific heat capacity for water is 4180 J/kg oC. My coffee cup holds 300. mL of tap water which has a temperature of 30.0 oC as it comes out of the tap. How many Calories of heat energy would be required to make a boiling cup of coffee? Why does a bimetallic strip made of copper and iron bends toward the copper strip when heated?A 150.00 gram sample of copper is heated in boiling water. After 10 minutes the copper is placed in a Styrofoam cup with 100.0 mL of water at 25.0 oC. The final temperature of the water and lead at thermal equilibrium is 31.0 oC. What is the specific heat of copper? 4. Here is twist on a familiar problem. In order to determine the height of a building, a student drops a 1.50 kg mass of iron off the top floor of a very tall building. The temperature of the iron block was 22.5 oC before it was dropped and it had a temperature of 24.0 oC after it hit the ground. What is theheight of the building? (Specific heat of iron = 450 J/kg oC)5. Aluminum has a larger specific heat capacity than copper. If equal masses of aluminum and copper wire are placed boiling water and then allowed to cool on the table, will one metal undergo a faster decrease in temperature, or will both cool at the same rate? Explain your answer.6. The specific heat of granite is 890 J/kg oC. You start the experiment by placing a piece of granite into a hot oven set at 450 oF (230 oC). After heating for 15 minutes, you place the granite into a Styrofoam cup containing 100.0 mL of water at 20.0 oC. The temperature of the water rises to 32.0 oC. What was the mass of the piece of granite that was heated in the oven? 7. Two equal masses of aluminum and copper are dropped from a very tall building and allowed to impact the ground. Aluminum has a specific heat capacity three times that of copper. Compare the two metals for the following:a. The GPE when released. b. The KE at the point of impact.c. The temperature after impact. 8. The nutrition label on a package of processed cheese food indicates that a 20.0 g serving has 175 Calories. To test this you put a small piece of cheese under a can with 100.0 mL of water and burn the cheese. You find that 1.0 gram of cheese was burned to heat the water. Assume that all of the heat released by the cheese was absorbed by the water (let’s pretend), what is the change in temperature of the water at the end of the experiment? 9. A student takes a 1.0 kg bag of lead to the top of the Empire State Building and drops it. The roof of the Empire State Building is 380 meters above the street. The specific heat of lead is 190 J/kg oC. What is the temperature change of the lead assuming that all of the gravitational potential energy is converted to heat? If the student repeated the experiment with a 1.0 kg bag of aluminum, which has a specific heat greater than lead, how would this affect the outcome of the experiment? 10. What is the advantage of connecting batteries in series? Parallel? 11. A flashlight contains 4 D-cell batteries connected in series. What is the overall voltage for the flashlight? 12. Compare the voltage, resistance, current and cost of operating a 60 W light bulb and a 100 W light bulb.13. Describe the properties of voltage, current and resistance in a series and parallel circuit.VoltageCurrentResistanceSeriesParallel14. Every electrical appliance sold in America has 120 VAC / 60 Hz embossed somewhere on the case of the appliance. What do these numbers represent?15. Use the circuit diagram below to complete the table. Assume the resistance of the bulbs is 15 Ohms. The voltage of the battery is 14.0 V.3153486680514.0 VABCDE14.0 VABCDEBulbVoltageCurrentA4.00 VB0.13 ACDEa. What is the total resistance in the circuit as measured at the battery? b. What is the total current in the circuit as measured at the battery? c. In the above circuit, which bulb(s) is/are the brightest? d. In the above circuit, which bulb(s) is/are the dimmest? e. What would happen to bulb A if bulb D were unscrewed? f. What is the voltage in all of the bulbs if bulb C were unscrewed? 16. Complete the table below. Assume National Grid charges $0.25 / kWh and the appliances are run for10 hours each day during the month of August.AppliancePowerVoltageCurrentResistanceCostAir Conditioner1500 WLight bulb600 Ohms ................
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