Download Physics 41 Exam 3 Practice HW

Physics 41 Ch 17/18 Quiz
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W
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SHOW WORK! NEATNESS AND COMPLETENESS COUNT. BOX ANSWERS.
1. A bubble having a diameter of 1.00 cm is released from the bottom of a swimming pool where the depth is 5.00 m.
What will the diameter of the bubble be when it reaches the surface? The temperature of the water at the surface is
20.0°C, whereas it is 15.0°C at the bottom. (Use ideal gas law for this! The density of water is 1.00 × 103 kg/m3.)
a)
1.05
b)
1.15
c)
1.45
d)
1.65
e)
1.35
2. Betelgeuse is a red supergiant star in the constellation Orion. It radiates heat at the rate of 2.70 × 1030 W and has a
surface temperature of 3000 K. Assuming that it is a perfect emitter, what is the radius of Betelgeuse?
A) 7.80 × 1010 m
B) 8.70 × 1010 m
C) 1.40 × 1011 m
D) 1.90 × 1011 m
E) 2.16 × 1011 m
3. A 5-kg piece of lead (specific heat 0.03 cal/g °C) having a temperature of 80°C is added to 500 g of water having a
temperature of 20°C. What is the final equilibrium temperature (in °C) of the system?
a.
79
b.
26
c.
54
d.
34
e.
20
4. A heat conducting rod, 1.40 m long, is made of an aluminum section that is 0.50 m long and a copper section that is
0.90 m long. Both sections have cross-sectional areas of of 0.00040 m2. The aluminum end and the copper end are
maintained at temperatures of 40°C and 280°C, respectively. The thermal conductivity of aluminum is 205 W/m∙K of
copper is 385 W/m∙K. The rate at which heat is conducted in the rod is closest to
A)
B)
C)
D)
E)
20 W
18 W
23 W
25 W
28 W.
5. A bridge is made with segments of concrete 50 m long. If the linear expansion coefficient is 12  10–6 / °C how
much spacing (in cm) is needed to allow for expansion during an extreme temperature change of 150°F?
a. 10
b. 2.5
c. 7.5
d. 5.0
e. 9.5
6. A 905.0 g iron meteor impacts the earth at a speed of 1629.0 m/s. If its energy is entirely converted to heat of the meteorite, what
will the resultant temperature rise be? (The specific heat for iron is 113 cal/kg•°C .)
A) 2810°C
B) 2,540,000°C
C) 3.10°C
D) 11,700°C
7.
a)
b)
c)
d)
How many particles of gas are in a bike tire with an absolute pressure of 7.00x105 Pa and a volume of 2.00L at 18°C?
3.00 x1023
b) 3.50 x1023
c) 3.50 x1027
d) 5.60 x1027
8. The average kinetic energy of a nitrogen molecule at room temperature (20°C) is
a. 2 × 10–21 J.
b. 4 × 10–21 J.
c. 6 × 10–21 J.
d. 8 × 10–21 J
e. 1 × 10–20 J.
9. Eleven molecules have speeds 16, 17, 18, . . . , 26 m/s. Calculate the root-mean-square of this group of molecules.
A) 21.2 m/s
B) 21.0 m/s
C) 21.5 m/s
D) 21.7 m/s
10. The temperature is increased from 20°C to 180°C. By what factor does the rms speed of a molecule change?
A) 1.2
B) 1.5
C) 3.0
D) 2.4
11. A 5.0-liter gas tank holds 1.4 moles of helium (He) and 0.70 moles of oxygen (O2), at a temperature of
260 K. The total random translational kinetic energy of the gas in the tank is closest to
A) 6.1 kJ.
B) 6.8 kJ.
C) 7.6 kJ.
D) 8.3 kJ.
E) 9.1 kJ.
12. An ideal gas is kept in a rigid container that expands negligibly when heated. The gas starts at a
temperature of 20.0°C, and heat is added to increase its temperature. At what temperature will its root-meansquare speed (thermal speed) be double its value at 20.0°C?
A) 40.0°C
B) 141°C
C) 313°C
D) 400°C
E) 899°C
The Cycle
A heat engine uses a monatomic gas that follows the PV cycle
shown. a. Determine the # moles, pressure, volume and
temperature at all points as well as ∆Eint, W and Q for each of the
three processes. Find the efficiency of the engine. Put your results
in a table for easy reading Attach your work.
e=
n=
T (K)
P(kPa)
V (cm3)
1
2
3
W (J)
12
23
31
Net
Q (J)
Eint (J)
ETH