Iced tea is made by adding ice to 1.9 kg of hot tea, initially at 90.0C. How many kg of ice, initially at 0C, are required to bring the mixture to 15.0C? (Lf = 3.33 105 J/kg, cw = 4 186 J/kg/C)
a. 1.6 kg
b. 2.1 kg
c. 1.5 kg
d. 3.1 kg
e. 1.7 kg
[Ques. 2] If a lamp has a resistance of 265 when it operates at 250 W, what current does it carry?
a. 1.0 A
b. 0.94 A
c. 0.97 A
d. 1.1 A
e. 1.9 A
[Ques. 3] A puddle holds 160.0 g of water. If 0.5 g of water evaporates from the surface, what is the approximate temperature change of the remaining water? (Lv = 540 cal/g)
a. +1.7 C
b. 1.7 C
c. +0.17 C
d. 0.17 C
[Ques. 4] If a lamp has resistance of 140 when it operates at 130 W, what is the applied voltage?
a. 135 V
b. 151 V
c. 121 V
d. 72.9 V
e. 108 V
[Ques. 5] A 0.0040-kg lead bullet is traveling at a speed of 220 m/s when it embeds in a block of ice at 0C. If all the heat generated goes into melting ice, what quantity of ice is melted? (Lf = 80 kcal/kg, the specific heat of lead = 0.03 kcal/kg/C, and 1 kcal = 4 186 J)
a. 1.6E2 kg
b. 5.8E4 kg
c. 4.6E3 kg
d. 2.9E4 kg
e. 1.9E5 kg
[Ques. 6] A 500-W heater carries a current of 4.0 A. How much does it cost to operate the heater for 30 min if electrical energy costs 6.0 cents per kWh?
a. 1.5 cents
b. 9 cents
c. 6.0 cents
d. 0.042 cents
e. 30 cents
[Ques. 7] Which of the following best describes a substance in which the temperature remains constant while at the same time it is experiencing an inward heat flow?
a. gas
b. liquid
c. solid
d. substance undergoing a change of state
[Ques. 8] If a 500-W heater carries a current of 4.00 A, what is the resistance of the heating element?
a. 85.7
b. 42.8
c. 31.3
d. 11.2
[Ques. 9] Two 0.95-kg masses, one aluminum and one tin, both at 80.0C, are placed in 1.00 kg of water at 20.0C. What is the equilibrium temperature of the system? The specific heats of aluminum and tin are 900 J/kg/C and 227 J/kg/C, respectively.
a. 32.2 C
b. 27.1 C
c. 13.2 C
d. 40.3 C
[Ques. 10] If a 600-W heater carries a current of 4.0 A, what is the voltage across the ends of the heating element?
a. 2 400 V
b. 150 V
c. 300 V
d. 0.0067 V
e. 4.9 V
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