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Unformatted text preview: So l u WE
Prohlem 1. (32 points} Answer the fotiowing questions and give brief explanations for your answers. Just stating
the answer without explanation is not sufﬁcient. Note. there are also questions on the back of
this page. i’tnswer all the parts! Each question is worth 4 points unless stated otherwise. {a} Two identical disks. A and 3, roll aeroﬁ a ﬂoor with equal speeds. Disk A then rolls up an
incline without shoeing1 reaching a height it. Disk 3 moves up an incline that is identical
except for the fact that it is frictionless. Is the maximum height that disk 5 reaches greater
than. less than, or equal to it? ' wk...th vhmwhw Kr;th the kﬂéa.
'19.“ .1th eh i hepLun_11~. agnfﬁ . M w am a so u... a: E m
{h} A. uniform block is Suspended by two wires1 A an 1 w 1 are 1enti : except for their initial lengths. The center of mass of the block is closer to
wire 3 than wire A as shown in the ﬁgure at the right. [1] Which wire exerts
a larger Force on the block? {2} If the two wires end up the same length. which one started out shorter?
(I) Tintr: '53 F.“ r“ a: Fl. r" Sitnu. (“if—ﬂ *5} E 3F”  F %= '5'} SM; F&?E.IIJ bLﬁhﬂLﬂ_ :‘J a SLOI'J‘HI' {c} r"; ltii‘i kg mass is suspended by a steel wire with diameter tint] mm and length iii at. You
measure that the wire stretches 1.6 mm under this lead. What is Young‘s modulus for the steel used in this wire? L. _.L. F e LE tinnitiouﬂ‘it‘itlﬂa)
9' t "' 1' Y“ em " 5 L Y A ﬁndin} TI: (assidlul‘ I I
{d} A oniliirni1 solid spherica hall of total mass M and radius R {left} .
is placed a distance R from a uniform spherical shell of total mass 2 M and radius R {right}. Raul: the order of the magnitude of the
gravitational force a particle of mass :l'l‘l: would feel if placed as the points labeled 1. 2. and 3 in the ﬁgure at the right. ,. .
FED 5M 3 gm of“; newt 3L“ J:er Mikey“... Problem 1 continued: {e} [ii paints] The spaee shuttle orbits EDD km share the Earth‘s surfaee. A sphere of mass Ll} kg
is inside the shuttle’s cargo ha}: [Nets: The mass at" the Earth is 5.98 x illillg‘d kg and the
radius ef the Earth is ﬁﬂi‘ﬁ it ID“ ml {1] What is the magnitude ef the terse ef tzrarittr
from the Earth felt by the sphere? {2} If net held in place the sphere will ﬂoat areund the earge hay appearing “weightless”. Hear is this pessible? m Fi GHEW‘ r: litrte 1»
3' r“ 1' span. 3m. ' I _ F P L. ‘ 1.:— Sﬂm Wt“  i r E [f] [B palms] Satellite A is in a eireular urhit of radius R. Satellite 3 is in a eireular (iihit el'
radius 2R. {I} ‘Wilat is the ratio of the orbital perieds 0f the twp satellite, TAfTET {2} [5:] As we mentiened in class if an nhjeet has all of its. mass inside its Sehwaresehild radiusI He.
even light eannet escape from it and we call this a black hole. Fer the Sun, Rs = 3 km.
Suppuse all the mass of the Sun eeliapses into a regien inside its Sehwarssehlld radius ereating
a black hale with the same mass as the Sun. humming ta Newton‘s them".' at gravity what
would happen to: the Earth‘s orbit? Haw meld it change? mam Mui «1:3: WW it settles”?
“lapses; FE: amps, A, frat. Hamish—3‘
at 1;.”th attendants“?!
its as all. sill ma. . ,«llss as mansiiietmmtmm_ ism "
itatJual‘Bid—J' Mal will Ll. ‘i‘t(SnJtua I? 9" 5 Lilian gum in Se. S o iuiﬁms
Problem 2. (16 points} You are at a playground sitting on the edge of a merry—go—round initially
at rest when a friend throws a ball of mass my to you. You catch the
ball when it has a speed 11b. The ttterryvgo—round can he treated as a
uniform1 solid disk of radius R and mass M. Your friend is standing
perpendicular to the top of the merry—go—I'ound and is at an angle E? with
reslmet to the horieontai. A top view is shown in the ﬁgure at the right. Anewer the following
questions in tonne of M. m, mm 1.43,, R, E, and rotManta, w appropriate. [a]: [2 points] As noted above you start at rest at point. A. After you catch the boil will the
merrygoround rotate clockwise or countercioeltwise? “(Llﬂm MT». and": —m w W t {h} to points] What is the angular speed, to, of the merryvgo—rouod after you catch the hall?
INA. '31:: =1 L = animal».
1..
L  “broLiaise” Lkm— LMLJ +(31HHJ earl . 1 Lt“? iHFrl hm. Timev:
Laid“: '5} <3l1H+ MirﬂlBobﬂit Mh‘lj'hkgmo 5") (c) [3 points] “Flten you get. to the top1 point B in the ﬁgure. you throw the hall directly
horizontally bath to your friend. You throw it with the same speed. ch, as measured by your
Friend. What is the angular speed of the merrygoIouad, of, after you threer hall? in what
direction will it he epinniug1 clockwise or counterclockwise? All£2. 44 LB: Immltm‘w'h‘w “EUUL
3'“ Thu—t =43 Wan1i" H4 whirr
Ln? Led—“L. —. L; 11‘“ ULH+M3 u'aho+mbgh — M whims amnesty, is April sec? 2 Fires 121 Exam III _ S a lo’lﬁ‘eS
Problem 3. (2e pellets} A speaker System i5 suspended by two cehlee labeled 1 end 2. The mess
of the speaker eyetem is M and the center cf “1.5.5.5 cf the system is Shawn
as a det in the ﬁgure at the right. The cables are. attached tn 3 meeeleee
trues eyetelu that is connected tn the ceiling at points A and B. Treat
the truee ea perfectlyr rigid. {a} [2 peintsi Drew 3 Free—lunchtijir diagram for the HpeakEr system. {b} IE paints] Find the tIL‘naiuIi in L E it'etlillers1 TI and T3. in terms (If MI, :11 and constants. ELE
appropriate. F355. r‘} TriﬂeHos
Te” “’1’ T163“): “‘3‘ * lieEH31 r {c} [4 paints] Drew a freebed} rliagrem fer the truee system. Treat the entire trues as a. single eye tern.
F Fa h ‘6’
‘4 :l—qac Clearly etete which directien the}r peint. Faee: =3. aiFaq: T'+TL= H3. TA?9 '5') Ti ‘2,“ 1113a"
:5 F5; Sini311? “i.
: (iiH.) H1. 'rVednceday, 13 April Eﬂﬂ? PHYS 121 Exam Ill ...
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This homework help was uploaded on 04/08/2008 for the course PHYS 121 taught by Professor Kernan during the Spring '08 term at Case Western.
 Spring '08
 kernan
 mechanics

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