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Unformatted text preview: Name: E \l/ PHY317K November 1, 2007 Signature: Exam 2 Unique number 61940
Instructions: 0 No notes= textbooks. or similar aids are permitted. (You may use a
calculator.)  Use the scantron answer sheet to provide the answers. Bubble in your name
(last, first) and UTEID. Write your name (last, ﬁrst), UTEID, course
name, unique number. Sign and date it. Mark answers for all problems.
Mark your answer sheet using #2 pencil. Mark only one answer per problem.
If you need another scantron, ask the instructor. 0 There are 16 problems on the exam. Each problem is worth 100/16 = 6.25
points. An incorrectly answered problem is worth 0 points. 0 You must complete this exam during the class period. 0 Any questions you may have about the test have to be directed to the
instructor or a TA. No conversations andfor collaborative work are permitted. 0 You may use the blank sides of the handout for notes and calculations. 0 Some equations and other information that may be useful on this exam are
provided on the last sheet ofthe handout. You may not ask questions about it.
You may detach it from the exam, but will have to return it with the rest of the
exam handout at the end ofthe exam. 0 On this exam you may always assume g = 10 int/52. 0 Sign the exam handouts and return them with the scantron form. l. A wheel,with rotational inertia I, mounted on a vertical shaft with negligible rotational
inertia, is rotating with angular speed am A second wheel with rotational inertia 21 is
initially not rotating, but is then dropped onto the same shaft, as shown. If no external
torque is applied, the resultant combination of the two wheels and shaft will rotate with
what angular speed? ' A) (Bu/2
@2590 Two 2 (00/3
D) 3600 a Io), ,, Io), _ w
E) (00/4 (’01? ’ “’ﬁ‘ fr“ ' ’2 112$ 31 3 2. An object, which is initially not moving, is released a distance d from the center of the
Earth . lfMis the mass of Earth, R the radius of the Earth, and d: 3R, the speed of the
object at the instant it hits Earth's surface is: A) m Au: —A\<
2m
C) m ‘19:“
D) JGM/R2 E) JGM/2R2 26M», i N3" =9 \I 46M H 2 GM ____,__._—..__ 8K 2 3R 3R 3. At time t = 0 a particle ofmass 4.0 kg has a velocity of 1?, =(4 m/s)? + (3 m/s)f. At t =
3 5 its velocity is 17'] : (—2 m/s)1'A. During this time interval, the net work done on the “in? NA = W = 5% Mt = 2%
‘ :42J ‘ L x L —
D; 25sz Ki, 3 l4ll5l — BOT E) K; = am (at) = 8 3“
W; AK : K¥_\<*\ : 9‘50 r—zllf 4. A uniform sphere and a uniform cylinder of equal mass and radius are simultaneously
released from rest on the same inclined plane. Both roll without slipping down the
incline. Then: A) they reach the bottom together because they have the same rotational inertia
B) the cylinder reaches the bottom ﬁrst because it has the smaller rotational inertia
C) they reach the bottom together because they have the same kinetic energy
@ the sphere reaches the bottom ﬁrst because it has the smaller rotational inertia
) none of the above is true
2 2 q 3 2 __
Igpkare : 7,: MR IQ \ “ ZMQ W) 15$an < :1:ch
04 : E. _ Slut: 73:1“ 1 ~> Asam > 0493) 5. A weightless strut is hinged to a wall and is used to support a block, as shown. A 3 m
cable, which is horizontal, is attached to the wall and to the end ofthe strut, as shown.
The hinge is frictionless and does not exert any torque on the strut. If the weight W of
the block is 1600 N, what is magnitude ofthe tension Tin the cable? 3m A) 600N
B) 900N
C) lOOON
® 1200N
E) ISOON 6. Cart A, with a mass of5.0 kg, travels on a frictionless horizontal air track at 4.0 m/s and
hits cart B, which has a mass of 15 kg and is initially at rest. After the collision the
center of mass of the two cart system has a speed of: A) zero A g A G.
B) 0.5 m/s 0 o «W \J
1.0 m/s *“5 —r> 5}
) 1.5 m/s VA E)20m/s Consecqu 6? MW“ "% 9:39;
MW». = (Mk‘rw‘raWs V3}: Mala 1 E—(ﬂ 2 lM/é‘ warms) L9H?)
7. A ball of mass 1.0 g is initially moving horizontally with constant velocity of 2.0 m/s. It strikes a wall and then rebounds from the wall with horizontal velocity of 1.5 m/s in
the opposite direction. The change in the momentum of the ball is:
A) zero B) 0.5N.sawayfromwall A 2 _ _ : m (V _V;
C) 0.5 N  s toward wall P Pi Q ) 3.5N  saway from wall __
Q 3.5N  stoward wall '3’ (l ' l S. 2’)
2  70 S N  s
AWA—Y FLEOM THE? NHL 8. A wheel has an initial angular velocity of 6.0 rad/s, but it is slowing at a rate of 1.0 rad/s2. By the time it stops it will have turned through an angular displacement of:
A) 12 rad B) 54 rad M = (0 “13/3 04 = fl “ml/g1 C) 26 rad (gig: LOG?) ’— wu Jr cit :> O ; b—ﬁ
:3 ~l: :1 E S
@(t): 90 4* wot, +£D<£1 go eats5% 0+ U0 “12%)?”
i We‘ll 9. A block of mass 0.5 kg slides along a horizontal frictionless surface with velocity 2 m/s.
It is brought to rest by compressing a very long spring of spring constant 800 N/m. The
maximum spring compression is: A)Ocm _\L> —> e—x
giil‘lmﬁ _m
23:32:: rib—AU 1 {EU
gm": glam =~> X: t:
I; 2 9‘5 <2)  tieQa 7 (aw 10. A constant force of magnitude 100 N is the only force acting on an object of mass 1.0
kg that starts initially from rest. At the instant the object has moved 2 m, the
instantaneous rate at which the force is doing work is: '2.
A) 1w
2) $50“! 0.: a "3 LOO M/g?’ X: gal: 50
) 50w L 1 =
D 1000w 504;” :2 =) JV, = E0 =) Jc 0.23
@2000w \§:\jo JrC‘x‘l: => V = 20%;
\9: 3;}: (\GOH)<Z©W‘/€l = ZUOOW l l. A uniform meter stick has mass 500 g. The meter stick has markings spaced 1 cm apart,
from 0 to 100 cm. The meter stick can be balanced by a weight of mass 125 g placed at
the lOOcm mark if a fulcrum (i.e., balance point) is placed at the point marked: A) 400m 6v; KW (Looﬁxy B 500m MN
60cm
) 70cm E) none of these “‘55 N35
Calcula—Jrﬂ Sum0Q it:qu Alood‘l‘ Has fslqut:
ratslog, 9N K {toga} M53 = (too ex) mg
Wtng r M3 (CO) : too WW3 ~ WWCAX (Mas + M) 34 : LOO mat * BONE»; k
too WW3 + $70 “53 5 “my léymy + (Sell extol 12. A particle of mass 3.0 kg moves to the right with velocity 10 rn/s, as shown. The
magnitude ofits angular momentum about the point P is: 10 m/s
3 kg .— ...................... —
\\
\ 30c
\\\\ \“~.
6 m \\ .P
\
\k_ /
._._3 A)zero Li’FX'é‘ =1) L‘er Six/we B) 180 kg  mZ/s © 90 kg v mz/s \
D) 24kgm2/s L: rm“ Sme E) 45kgm2/s : (Mpgx \o} gilt/\FDJOO
:: “2/5 13. The rotational inertia ofa solid uniform sphere of radius R and mass Mabout an axis
through its center is (2/5)MR2. A massless string, of length 2R, is attached to such a
sphere at its surface and used to suspend the sphere from the ceiling, as shoWn. The
rotational inertia of the sphere about the point of attachment to the ceiling is: Parallel OL‘L'LS Wayem: i ~ ~ .c as I a. :0m + MW
: §MQZ+ MCngz
: EMQZ +OtMlZl
2: ﬁg, MR1 A) (2/5)MR2
B) 9m2
c \16MR2
my), (47/5)Miz2
E) (82/5)MR2 14. A spherical shell has inner radius R), outer radius R2, and mass M distributed uniformly
throughout the shell. The magnitude ofthe gravitational force exerted on the shell by a
point particle of mass m which is located inside the shell a distance d from the center ie., d < R;) is: I
0 Rf Ck 4 Rt W ’5 M ) GMm/RE I ‘ JCQ du—Q
C) GMm/(f ooAl‘thu’tm in W [5:0
D) GMm/(R32~d2) +6 W85 M ‘ E) GMm/(R. a d)?
¥tt<@)10 15. A block of mass 10.0 kg is released from rest 20 m above the ground. Ignoring air resistance, when it has fallen 3 m, its kinetic energy is approximately:
A) 30 J B) 601 AK: fAU = — we%Al/\ C) 100] (3333i AK= ~(to)(m)(—S) : 3003 16. Block A, with a mass of4 kg, is moving with a speed of2.0 m/s. Block B, with a mass
of8 kg, is moving in the opposite direction with a Speed of3 m/s. The center ofmass of
the two blocksystem is moving with approximate speed: A) 1.3 m/s in the same direction A is moving M g i M;
1.3 m/s in the same direction B is moving
@ 2.7 m/s in the same direction A is moving
D) 1.0 m/s in the same direction B is moving
E) 5.0 m/s in the same direction A is moving CQACAJ \fcwx ' \ICJAA. : AA} Z MJVJ \ICM 4+8 \2 ‘2 _ 4(2) +8033: @424 H1tt:_\_swg ...
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 Spring '07
 KOPP
 Physics

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