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Unformatted text preview: PHYS 218, Exam 3 Tab le 8. 2 Moment of Inertia for Some Common Objects“ 631m SNAPE OBIECT SHAPE
Iloop Rod pivoted at center
I = mRZ I = 11—sz2 l
5 I'd h
o 12 SP :re Pulley/cylinder/disc
I = me I = %mR2 Wheel or hollow cylinder
1 = immim + Rim) Spherical shell
I = §mR2 FOd pivoted at one end 6, i g Solid square plate with axis Ql a I = imLz er endicular to late ‘ 7
I P P , p 7 Density of water, 9mm = 1000 kg/m3 Acceleration due to gravity, Igl = 9.8 m/s2 Kiwi Brion A lac w» (Last) (First) (Middle) Name: 1. Record ”82” as your two—digit exam version number on the scantron form in the ﬁeld “TEST / QUIZ
NUMBER”. 2. Write your name here and on the scantron form. 3. Record your PUID number in the “STUDENT IDENTIFICATION NUMBER” ﬁeld on your scantron form. 4. A numeric answer that is correct to within 1% error is considered correct. 5v» 1. A suction cup works by Virtue of a vacuum that is created within the cup. When the cup
is pressed against a ﬂat surface, most of the air is forced out, leaving a region of very low
pressure. For a certain cup of area 1.4 cm2 it is determined that the most massive object it
will support on earth has a mass of 0.48 kg. What is the most massive object that the same
suction cup will support on the moon where gravity is 1 / 4 that of earth and where there is
zero atmospheric pressure. (a) 0.48 kg (d) 1.92 kg 5“” (b) 0.12 kg H v 9.5.59 .3 92:: RM. 1% map
a“ i“ M “RN ydkn c mvvbT éwqxl‘br‘b 099% w:— \
2. A person carries a pole of total mass 2 kg and tota ength 3 m. ne mete of the pole dangles
behind the person’s shoulder as shown in the ﬁgure below. 17. \ﬂ \ (c) 336 kg EV?“ (e) None of the above. /‘ T” rut, m .._.. hide it
7 a? z) 5 b Cztfid‘ Vi”
F? it Find the magnitude of the torque about the person’s shoulder due to the weight of the pole. 1 05M 'l" vatSJ (a) 39.2 Nm (d) 19.6 Nm (bi 9.80 le
(c) 4.90 Nm (e) 58.8 Nm “Ti. lav
: LB‘lsg. . 0.3.. 11% NM 3. A bicycle rolls without slipping over a distance of 10 m, during which time each tire makes 4
complete revolutions. What is the radius of a tire? a 0.796 m (d) 2.5 m
(b) 0.398 m
(C) 15.7 m (e) None of the above
g .
_ _ —— [O M
5.; 9r 9 r“ e r~ : orswu 3‘ ”WWW =5 ‘l‘ K'LK allow; LlXL'W 4. The ﬁgure below shows a plot of the position, as, as a function of time, t, for a particle
undergoing simple harmonic motion. x 1
2
3 t
——>X For which point is the acceleration of the particle zero? (a) 1 (d) 2
(b) 4
(c) 3 \ (e) None of the above. +0 ”lo AAA» T5 Jr» msl‘c “ll/d— ”ll’t. ‘C'vm 5. A chest of volume 3.4 m3 ﬁlled with gold (pgold = 19, 300 kg/m3) sits at the bottom of a lake of depth 10 m (Pwater = 1000 kg/m3). What is the magnitude of the normal force exerted by
the bottom of the lake on the chest? (a) 610,000 N (d) 24,500 N
(b) 676,000 N
(0) 643,000 N (e) 98,000 N ~. éo‘ﬂse 11
T O .. N * _F\m~uj*:F\jrau (“Ckse’v‘é 13+: guns
Ev; N = 43.43” ”v3.0  — mm 0 + was
:Fsran/ 2 +Vé Gfu‘ﬁud. 4' €5b®c 3‘!“ 1.964000% ('{390> 6. A rod of mass 4.0 kg and length 2.0 m hangs from a hinge as shown in the ﬁgure below. The
end of the rod is then given a “kick” so that it is moving at a speed of 2.2 m/s. L 4263?? rod I L‘ Hinge
/ E —> vi = 2.2 m/s Caulk4
o'P “4.45 How high will the rod swing? Express your answer in terms of the height of the rod center—
of—mass, relative to its initial height. (a) 0.247 m (01) 0.0823 m (b) 0.807 m (c) 0.0374 m (e) None of the above.
AF: = O 7. A student of mass 100 kg is sitting still on a freely rotating stool holding a rotating bicycle
wheel, a situation similar to our in—class demonstration. W
$33”.me ﬂip Wheel Initially, the angular velocity of the bicycle wheel is 10 radian/s and its mass is 0.5 kg. The
radius of the bicycle wheel is 1.414 m and you may assume that all of the wheel’s mass is
along the outside rim. The student ﬂips the bicycle wheel over and he begins to rotate at 1 radian/s. What is the magnitude of angular momentum of the student after the wheel is
ﬂipped over? (d) 0 kg m2/s (b) 14.1 kg m2/s , ’
(C) 25 kg m2/s (e) 1 kg m2/s O (5%: :4le
Al.— : O : AL fl‘vQJa/Cl =1 Lil’wvlwJf‘g g L whol”, 2 Li, Y.
= O .1“:
Al’ka J“ AL‘M‘J : O ’ Lyceum” , ALLJl—oul g, S ALJJCM 12' " AL ule\ 3 s I (Dd — 1.0;) ': mk’LOJFDQ': "5.15mi. ((0:10) 8. A solid spherical marble (radius 1.1 cm and mass 10.0 g) approaches a very tall hill. Its
initially velocity at the bottom of the hill is 2.4 m/s. To what maximum height up the hill
Will the marble climb? Neglect air drag. (a) 0.294 m (d) 0.411 m
(b) 0.140 m
(c) 0.171 m (e) None of the above. "VE ~KEL=C> KS ._ _, ~ .L z
Veg—(KR (0+ 1 Kayak = O 5 lo we ~35 24‘
5 «———~ : .1/1 .411 t.
1 L 3 72' w l’\— 2100; 4' "MUSC 3' O 9. Say you are constructing a building and you need a 4 m tall cylindrical column that will
compress less than 2 cm under a load of 105 kg. The Young’s modulus of concrete, Y can
vary between 20 X 109 Pa and 50 X 109 Pa. What is the smallest diameter concrete column that you can buy that will guarantee that the
speciﬁcation of less than 2 cm compression under 105 kg load is met? The area of a circle is
D27r/4, where D is the diameter (a) 0.20 m 
(b) 0.10 m M (C) 005 m (e) 0.25 m 3
F . .9":  ‘ E, L; just M. 0.59 35M Jj Ll): 10 G“)
K= L “7 A  Y AL. t. w w, ,QDW ’wa
OS lL ﬁg?” Ll IM 2. Tr ‘— 4A — 0 00 g
A3 —L——é——’"" ——’“‘ a 00518 “7’ :3?? ‘D.§; _ Ll T7 = O. I(
10. A plank of total mass 5.8 kg is sitting on two supports, as shown below. What force db‘es the right—hand support exert on the plank?
< 3.0m + 7.0m + 2.0m 4 (a) 25.3 N l (d) 24.4 N i
(b) 171 N
(c) 2.49 N (e) None of the above. ...
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