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Unformatted text preview: Physics 2750
Review Exam 4 1. A cup is ﬁlled to the brim with water and a ﬂoating ice cube. Resting on
top of the ice cube is a small pebble. When all the ice melts, which of the /
following occurs? , I _ I r
a) water overﬂows the cup; El“ Vf ' 3? U? %/
the water level decreases \J
c) he water level remains the same. :5 VA; ‘“ g]: ' My. 7 ?
.1 7 L 2. Two containers of equal volume each hold an ideal gas. Container A has twice as many molecules as
container B. If the gas pressure is the same in the two containers, is the rms speed of the molecules in . 1 ,
conta1ner A 2,7 A H a" 61$}! PA \JQ’ :. I”; 6‘1 M
a greater than, L «3 {9? 2" V " l“
less than, or \/A '— Z x 7, V y H
c) the same as the rms speed of the molecules in container B (W «a p .t "‘l L V2 I) Ha _
r. ‘ §ET . r” cl :) J ; ~EJ;Z_
3. A gas mixture of hydrogen and argon molecules are in a container held at a constant 68°F. Which of the
molecules has the greater average speed? I, “L _ '9 k1?
: w M V ~ I
K 2, l “E L (03’ the hydrogen because they are lighter
c the argon because they are more massive
d) uncertain because we need to know if hydrogen is monatomic or diatomic I neither, the same temperature produces equal speeds 4. A wooden block ﬂoats in water in a sealed container. When the container is at rest, 25% of the block is
above the water. The container is now lowered in a ﬂuid at constant speed. The air pressure above the water in the container is increased. What happens? a The block ﬂoats higher in the water
The block ﬂoats at the same level in the water c) The block ﬂoats lower in the water
(1) The fraction of the block above the water cannot be determined from the information given 5. A square box of wine has a small spout located in one of the bottom comers. When the box is full and g . . . . . . /
s1tt1ng on a level surface, completely open1ng the spout results 1n a ﬂow of w1ne w1th a speed of v0. The l E box is now half empty and still sitting on a level surface. When the spout is completely opened the wine l L
will ﬂow out with a velocity of l ’ W?
a) v0 b) v0/2 @vo N5 (1) v0 /2“4 6. A U shaped tube contains two different ﬂuids of different densities. Both sides
are open to the atmosphere. Which pair(s) of points have equal pressure? a) P1: P5 /> We mhAvsqgﬁALgc. WM... b) P2 = P5 cP=P F) ._ I . B30th (:1) and (SQ \W l? “mm Wag e) «Both (b) and (c) 7. In many cartoon shows, a character runs of axicliff, realizes hispredicament and lets out a scream. He
continues to scream as he falls. If the physical situation is portrayed correctly, from the vantage point of
an observer at the bottom of the cliff , the pitch of the scream should be:
Higher than the original pitch and constant
Higher than the original pitch and increasing as he falls
c) Lower than the original pitch and constant
d) Lower than the original pitch and decreasing as he falls 8. A massless cylindrical can of radius R is ﬁlled to a height H with cement. When the can is placed in a bowl of water with density p it ﬂoats upright with the bottom of
the can a distance 2H below the surface. What is the mass of the cement? a) pw7z'R2H :6: W]
b) pWZﬂRZHg (Kati)? : my @pwzﬂRzH w " .3 "z? ‘
" : {mt R. H
d) png m gut} K... the uniformity of pressure at the same level in a ﬂuid 7 ) the weight of its large piston
c) the much higher pressure on the large piston than on the small one
d) Archimede’s principle 9. A hirdraulic lift has a large piston and a small one. It can lift heavy cars because of: 10. If 3.5 kg of molten Tungsten solidiﬁes at its melting temperature of 34100C, what is the entropy change? The latent heat of fusion for tungsten is 1.84 x 105 J/kg. g“ \ (.33 32,21
a) 159J/K g «Q ~N7L 935,. Again?) __ Calm“g : [111,3 W;
_ : v”. 5 ’ 3 M MM" ' 7
b) 159 J/K A, T T Cy! \ 0,, 24.3) ﬁst; ,1 , 175 J/K
‘ —175 J/K The following text refers to the next two problems (: An ideal diatomic gas is initially at temperature T
and volume V. The gas is taken through three reversible processes in the following cycle: adiabatic
expansion to the volume 2V, constant volume process to the temperature T, isothermal compression to the original volume V. i
l w 3
ll Fr the complete cycle described above, which of the following is true? N Net thermal energy is transferred from the gas to the surroundings. Z
i The net work done by the gas on the surroundings is positive. "l‘hw‘w" 19)” The net work done by the gas on the surroundings is zero.
The internal energy of the gas increases.
yr The internal energy of the gas decreases. / f i m 0. W3 “xi treats." (“mi err mam, tia \ iir’larz, levo 15K: JrlA Uriah" \ \l (W
\ 1 T "' 13 teams”. 3A,? 1 ls» I
12. Which of the following statements about entropy changes in this cycle is true? a)\ The entropy of the gas remains constant during each of the three processes. b) The entropy of the surroundings remains constant during each of the three processes. The combined entropy of the gas and surroundings remains constant during each of the three
_ processes.
d) For the complete cycle, the combined entropy of the gas and surroundings increases.
e) For the complete cycle, the entropy of the gas increases. 13. A block of wood has a mass of 3.67 kg and a density of 594 kg/m3. It is to be loaded with lead so that
it will ﬂoat in water with 0.883 of its volume immersed. What mass of lead is needed a) if the lead is on
top of the wood and b) if the lead is attached below the wood? The density of lead is 11400 kg/m3. ' “)1 . a I“??? ,ﬁ :ﬂum w... => wry Nag—r WW 1 ‘z/ v4 : M892 VW W Mr‘” . _ WM
, V I : K WW”; I j W 1
WW 83"“? [O w W W N VD Qikzo' (02% 2Vw+ Val; N w '1’ 171) B 1“ WMLBIZELBL: ” “81.010 3 w a». “U “
a r """ , , ,
vlvflb'h'iwih «> w = W. ' ‘Yb
14. A submarine at a depth of 200 m develops a relatively small leak. At what speed does the water enter
the sub? Assume that the air pressure inside the sub is the same as the air pressure at sea level. ® :3 {was Pr: 6333+ .t. 1‘" _ ~. , ,2 .,
«Shrew» w W?“ " gm “t a n: {2751 ; Qﬁp Iii/5 /
_ v? 15. A 3.5 kg block of copper at a temperature of 80°C is dropped into a bucket containing a mixture of ice
and water whose total mass is 1.2‘kg. When thermal equilibrium is reached the temperature of the water is
8°C. How much ice was in the bucket before the copper block was placed in it? or maﬁa/Ti) . cl 1 5040 M125 1:. a. “#217; “1.3 we = m we we: Mu» 1at *’ W
Z r 11111 if. J «1 .7
/ Q5: Nztnitc F f\ lﬂ’m : 3‘%3*'O szcTB =10 0W: WBC (l£“12) WAX{vim}: 1‘7, 3,
;> Wtcrbp"b~t(wzjtw§\cw (1 '15—1 “771141, 7’0 ...
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This note was uploaded on 04/30/2008 for the course PHYS 2760 taught by Professor Kozstin during the Spring '08 term at Missouri (Mizzou).
 Spring '08
 kozstin
 Physics

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