Questions

Note: Neglect all frictional forces in all exercises.


1		The Fahrenheit temperature reading is 98° on a hot summer day. What is this reading on the Kelvin scale?



2		A 0.25 kg length of aluminum wire is warmed 10.0°C by an electric current. How much heat was generated by the current? (caluminum 5 0.22 kcal/kgC°)



3		A 1,000.0 kg car with a speed of 90.0 km/hr brakes to a stop. How many cal of heat are generated by the brakes as a result?



4		A 1.0 kg metal head of a geology hammer strikes a solid rock with a velocity of 5.0 m/s. Assuming all the energy is retained by the hammer head, how much will its temperature increase? (chead 5 0.11 kcal/kgC°)



5		A 60.0 kg person will need to climb a 10.0 m stairway how many times to "work off" each excess Cal (kcal) consumed?



6		A 50.0 g silver spoon at 20.0°C is placed in a cup of coffee at 90.0°C. How much heat does the spoon absorb from the coffee to reach a temperature of 89.0°C?



7		If the silver spoon placed in the coffee in problem 6 causes it to cool 0.75°C, what is the mass of the coffee? (Assume coffee 5 1.0 cal/gC°)



8		How many minutes would be required for a 300.0 W immersion heater to heat 250.0 g of water from 20.0°C to 100.0°C?



9		A 200.0 g china serving bowl is warmed 65.0°C when it absorbs 2.6 kcal of heat from a serving of hot food. What is the specific heat of the china dish?



10		A 1.00 kg block of ice at 0°C is added to a picnic cooler. How much heat will the ice remove as it melts to water at 0°C?



11		A 500.0 g pot of water at room temperature (20.0°C) is placed on a stove. How much heat is required to change this water to steam at 100.0°C?



12		Spent steam from an electric generating plant leaves the turbines at 120.0°C and is cooled to 90.0°C liquid water by water from a cooling tower in a heat exchanger. How much heat is removed by the cooling tower water for each kg of spent steam?



13		Lead is a soft, dense metal with a specific heat of 0.028 kcal/kgC°, a melting point of 328.0°C, and a heat of fusion of 5.5 kcal/kg. How much heat must be provided to melt a 250.0 kg sample of lead with a temperature of 20.0°C?



14		A heat engine converts 100.0 cal from a supply of 400.0 cal into work. How much mechanical work was done?



15		A heat pump releases 60.0 kcal as it removes 40.0 kcal at the evaporator coils. How much work does this heat pump ideally accomplish?

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