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Unformatted text preview: 1. As shown in the picture, a stick of length l = 3 m pivots about its left end
at the origin. A force F with magnitude 6 N and direction 60° down from
horizontal is applied at the middle of the stick. What is the torque about the origin? a)
b
c)
d) 6) 7.8 Nm r
4.5 N'm ﬁg 0 Nm 3 .2
9Nm K’tltlixﬁl
15.6 Nm 3 r F shag :(\.Sm)(gro)(sm 60") .~ 7.8m», 2. A grindstone is a solid disk with mass 10 kg, radius 0.2 m, and moment of
inertia of 0.2 kgmz. You put a knife blade against the outer rim, and exert
ing constant force give it an angular acceleration of magnitude 5 radians/s2. What is the frictional force that you applied? 'Xsicl; rpéi‘ne @ gag; . :5F I‘aL/v
herc 5 me :5. "
b) 0.08N “ "WW I .. o 235 : 5H
d) Cannot be determined without knowing coefficient of friction ,u.
e) 0.05 N 3. A skater, spinning on the ice, wants to rotate around faster. Which of the following should she do? a)
b) 0) 9“ch Lsiw o5 wnsERvED/ Hold her arms straight out to both sides. Wm,» Wu ﬁg I 3 Eda): p r1
Hold her arms straight out to her front. ""
Put one arm straight out forward, and the other straight out back ward. BY K as PING.
Y‘ SWU ﬂ Hold her arms tig in against er tummy. 6) The position of her arms does not matter, so the other answers are
all wrong. 4. Which of the following is true if there is static equilibrium? 9+a+“c .5160“ i {brulm a)
b)
6
d) e) The sum of all frictional forces is O.
The sum of all torques is 0, but only about the center of mass. 3 F30
Diana The sum 0 a torques is . i t : 0 Each force has to pornt directly towards the center of mass. Each force applied has to create a non—zero torque about the center ’90“ all of mass. .Cbrecs) qn“
gar al\ fugue; 5. A uniform 2 m long rod has mass 2 kg. Attached to it is a small 0.5 kg
mass at the left end, and a small 0.75 kg mass at the right end. How far
from the left end of the stick is the center of gravity of the system? a 1.27m , . ' M ‘ ‘ 2
bi 1.69m YUM: éww‘¥* 2 @‘Slﬁml'l' Q—“Qfl 3*05‘5i M) 0 2.00m 2M; 0515 +233. g—fLS’lra d 1.08m
Slc. '
e) 1.20m YUM 2 .3 \‘O%m 6. A shelf of mass 5 kg sticks out 50 cm from a we. 1. It is supported by a cable,
attached to the outer edge of the shelf and to the ceiling directly above. A
small 2 kg mass sits at the center of the shelf. What is the tension in the 7. A 0.5 mm radius steel Wire, with Young’s modulus 2x 1011 Pa, supports a 7
kg mass. When not stretched, the Wire is 2.4 m long. What is the strain? b —5 . Ma :r F
$+Vq 8:. p... :  r: m
m 9. Y AY (1) 4x10"4 mm
e) 1 mm
2': @l‘ah‘gh‘é‘) thlod'l
17 (may?) 2&1: 09“ Pa) 8. Flag 3 37,“: A
Siave Wagons. «we. at “Ski '43 1'0 cud» : 9. 10. 11. Three identical 1000 kg masses sit at on three corners of a square, with
sides 1 m long. What is the magnitude of the total gravitational force on
mass B, from masses A and C? amt/v1 =E<E1¥~lvfjéoa>2ﬁL : l ,. other)
a) 6.67x105 N b) 1.33>< 10—4 N c 9.43>< 10’5 N d 8.90x10‘ N e) 0 N — the forces are in different direc
tions and cancel Your weight on the earth is 600 N. On the moon, your weight is z100 N.
The diameter of the moon is @3500 km. What is the mass of the moon? a) Cannot be determined from the information given. b) 3X1023 kg Your mass (9 m: 98 (5:: GOONI‘ikS‘h]; :€\V~g c) 7.7><1015 kg ;
d 7.7X1021 kg :62 [V1) 50 m '.: Sail: QDON)(1.75¥tOLm a. remumw The moon Titan orbits the planet Saturn at a distance of 1.22 million km
every 16.0 earth days. The moon Tethys orbits Saturn with a 1.89 day
period. Assuming circular orbits7 what is the radius of Tethys’s orbit? a Cannot be determined without being given the mass of Saturn. 1...
{hi 0.29 million km) {lug have. v" :: CONﬁTmJT
r~ Ham mu 9M: 5
c) 0.05 million km am“ “’2 ’ e) 30 million km ’3; 1' —;,;_ :7 Te. I, “n
a T‘
r?! *0. '1'! ‘ 3“ 2/ A rocket leaves a small comet of mass 2.><1020 kg. At T = 104 km, its : (3”)3 L7.
engines have stopped ﬁring, and it has 7) = 0.1 km/s. The rocket coasts out ‘4’ z  ' ’ 7 I: ~
to 7' Iooé1 What is v wh:n it get: there. h d 1 \ “({hk“ t t t t  't t 't .
o o ge ere l as no reac e escape ve 001 y j a a4. by Co
11)) 861118 LMU;_G‘MW «J. 42 G
C m/S L ¢:~ " z "‘
d) 1630 m/s ‘ I
e) 113 m/s z) a"? :. 0'“. 1.6194 :Qboy‘ ‘ OXL.DXIG"“)(1‘“°
r~ \ ’2 ND“l l2». .. LL9
0' .. Lbooo z o Conuwkqumﬁta 09:56, "45 12. 13. 14. 15. A submarine dives 30 m deep into a lake (pwater 2: 103kg/rn3). Pressure
inside the submarine remains at 1 atm. Ignore the support forces from the
submarine, and calculate the net force on a submarine window of area 0.5 2
m from the pressures. 1p,“ : Padm L/ maﬁa/W: gang?! y gom
a) 0.5X105N _. + 52
b 1.0><105 N pvvrv 17‘9"“ ﬁg“ (Evmoo a;
c) 1.5x105N
2.0x10 N CH,» {Pom‘13.“) an Area
e) 2.5x105N : gov(000') 9Q Y O¢SMLQ A wide, tall cylinder nearly full of water has a small hole in the bottom,
through which water is ﬂowing out. When the water is 0.3 m high within
the cylinder, what is the speed of the water as it flows out? 3 wﬁwulj Prrncﬁ, Le a) Need areas for hole and cylinder to determine this. b 24. 2 A :2 i
c) 7.7 IIIIll/SS 26*? “2"Pﬂl‘ 3:" " 21‘7" *ﬂz/
d) 2.4 m/s .: Pam v: 0441a? : 7am h=o “+59%,
8 . m S ‘42.). ’h
50 p6 2’9 “M U” ‘ W: ZX‘LeXm?) A rectangular plastic block of weight W floats in a tub of water with exactly
twothirds of its volume below the waterline. Which of the following is true? 1g Ark lovebcml— gercg a) The buoyant force is 2W / 3. a
b) The buoyant force is W/ 3. M 569.“ ﬁg. wexﬁ lai j 14
4‘90) c) The density of the block is pwater / 3.
d) The density of the block is Spwater. e he uoyant force is . Water is ﬂowing through a pipe whose radius increases from 3 cm to 9 cm.
The water is moving at 21 cm/s in the narrow section of pipe. What is the
speed of the water in the wider section? (0490\0k move. , ’2.
pbimlc : § pawn" a) It depends on whether the pipe is vertical or horizontal. ‘23 Sign}? v’ A = WV
W 0” 2 VLA‘) Zlfm/ﬁ ‘ V (3“);
A (Clem);
0' 7— 7% Chi} ...
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This note was uploaded on 03/02/2012 for the course PHYSICS 124 taught by Professor Madey during the Spring '08 term at Rutgers.
 Spring '08
 Madey
 Physics

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