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Unformatted text preview: PHYS 1111, Section 3, Fall 2011
Test no. 4, version 1 November 29,2011 K E ‘1
11:00am — 12:15pm Alﬁﬂﬁ.thammammmaqVZWnudau?chat:pmmﬂbns13eﬂﬁgpn¢kmuamanqwﬁu¢thﬁuﬁeaumaZ
anyﬁrdmuujmwuulmﬂﬁnwuvnmngdhuknnﬂzandannnmsandbmammnnmhxzIanmqykgpnk!
pnwﬁmvmhwrwﬁazumvanyﬁnﬁbadzﬂrayaadhnmhuﬁqnnanxantheﬂumpqya TRUE/FALSE. Choose 'True' if the statement is true and 'False' if the statement is false. 1) For a periodic process, the number of cycles per unit time is called the period 1) 5
c/ci 
A)True B)False f: .22....— = frezumC7
f 3m e 2) In a potential energy diagram, an equilibrium point corresponds to a location where the slope of 2) A the potential energy curve is zero. A U
(A) True > B) False E Z V A X MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 3) Two equal forces are applied to a door. The ﬁrst force is applied at the midpoint of the door; the 3) A
second force is applied at the doorknob. Both forces are applied perpendicular to the door. Which force exerts the greater torque about the door hinge? __./ ,0 “’4
A) both exert zero torques b:
B) the first at the midpoint .. If If
C) both exert equal nonzero torques Z: 3 [.33.
< E) the second at the doorknob ) 2 F _ F
, l E) Additional information is needed. 2‘ I F2
Lu. 4) A hoop with a mass of 2.75 kg is rolling without slipping along a horizontal surface with a speed 4) J 2
of 4.50 m/ s when it starts down a ramp that makes an angle of 250° with the horizontal. What i the rotational kinetic enera of the hoop after it has rolled 3.00 m down the ramp? q
A) 62.0] (
F G“
B) 34.2] Use (mum/Mob 0 my; 1
022.4] f . _ ,'__
gnaw) E_K+kr—+U9_ WM 6—,E7A
l 5 question cannot be answered without knowing the radius of the hoop. W/ 2 z
..,L —~L .1 3mg
:tIUfZJELMQZ (57)“ vaf‘z 06/, +071 9 j ~— 5) An object is made up of three masses connected by massless rods of ﬁxed length. Mass A is 5) é
located at (30.0 cm, 0 cm) and has a mass of 250 grams, mass B is located at (0 cm, 30.0 cm) and
has a mass of 350 grams, mass C is located at (30.0 cm, 0 cm) and has a mass of 450 grams. What is the moment of inertia of this object about an axis perpendicular to the x—y plane and
passing through the origin? ‘1 T ( Z M r,‘ 2_ A) 00135 kg m2 B) 0.315 kg m2 C) 0.0450 kg m2 1» ‘ D) 0.185 k m2
0.0945 k m2 6) For the angular momentum of a system to be conserved,
4" l J A) the moment of inertia must remain constant. ”V ;@.2rka)(o.3m)z + (0.30613); 2 +(o.45)(o,377’ ” 0'0?“ l7”
6) L (ac/[0’ c4 (‘15 ‘ o M
m (I; to” B) the angular velocity must remain constant. .27 Col/(J CA M? e
0“" o\' C) the angular acceleration must remain constant. \> Co “(J 6/7 #65 e a
lot 31V D) the net external force must be zero. r? C « A L A
/‘ ' — A
E) the net external torque mus e zero. . ”(+13 ._> . F A
‘ o :A L. A? ’ ’ I!2 D
7) When you ride a bicycle, in what direction does the angular momentum vector of the wheels 7)
point? A q—A
gamed: v E ”W
ac war s
C) to yourright b? ”55% Ban] rally;
W "'8 P05('¥’\lt i’ (’9 an
i 8) A woman is holding an 8.00kg vacuum cleaner at arm's length, a distance of 0.550 m from her 8) C shoulder. What is the torque on the shoulder joint if the arm is held at 300° below the
horizontal? A) 12.6 NE(V> & B) 21.6 Nm C) 37.3 Nm D) 2.20 Nm E) 4.40 Nm f: Mj/meﬂ ‘—' @F6)(135%)[affo”)(fmo”) : 237.3 Mm] 9) What is the quantity used to measure an object's resistance to changes in rotational motion? 9) Z S B) torque 0 f "' 0<
C) angular velocity 2 C "' 4! D) angular acceleration 7\ E) mass 10) The drive chain in a bicycle is applying a torque of 0.850 Nm to the wheel of the bicycle. Treat 10)
the wheel as a hoop with a mass of 0.750 kg and a radius of 33.0 cm. What is the angular acceleration of the wheel? .—— 7_
A) 20.8 rad/52 Z 1 IA ,L : MR
B) 1.06 rad /sZ m A,
C) 3.43 rad/$2 d I: .9. ,. C . W :
D) 5.20 rad/52 I " ’ 7, ‘Z
Hﬁ (0,757?) 633/») 11) A mass of 375 g hangs from a string that is wrapped around the circumference of a pulley with a 11) .B moment of inertia of 0.0125 kgm2 and a radius of 26.0 cm. When the mass is released, the mass
accelerates downward and the pulley rotates about its axis as the string unwinds. What is the tension in the string?
A) 1.84 N B) 1.21 N C) 2.45 N D) 3.68 N E) 0.605 N 7% ®
. ( 2) 7h
’ mo. 43): €“:Io< “51’1”“ 12) The L—shaped object shown in Figure 1 consists of the masses connected by light rods. How 12) B
Wk done to accelerate the object from rest to an angular speed of 3.25 rad / s abou the ~axis?
A; 27.4y] C) 42.2] D) 86.5] E) 374 J
W: mark; : flex/ﬁlo .
:; J—(32.67 Igmﬁﬂzfﬂ :(Hg 3; 13) In sim ole harmonic motion, the speed is a minimum . t that point in , e cycle when
A the magnitude of e . lsp acement is a max1mu U
B) the kinetic energy is a maximum. X I "\\. C) the magnitude of the acceleration IS a minimum. X\
D) the magnitude of the displacement' 1s a minimum} 14) If you take a given pendulum to the Moon, where the acceleration of gravity is less than on 14) A E e oscillation frequency of the pendulum will
A) decrease. M I 3 1 5;" < 5L?
L. B) 1ncrease.
Mm 4 («FE C) not change. D) become zero. E) either mcrease or decrease; it depends on its length to mass 2rJratio/r
I 15) A sewing machine needle moves with a frequency of 2. 5 Hz. Approximately how long does it 15) 5 take it to move from the highest point to the lowest point in its travel?
X A) 0. .10Ts B) 1.25 s C) 0.40 s D) 0.80 s E) 0 20 s
é—— ...—<7
A A t = T _ Z (I
" ~ 9 6 2 17° C 2(25'ﬂe] 5 0'25 B
16) An airtrack cart is attached to a spring and completes one oscillation every 5.67 s. At t = 0 s the 16) D
cart is released from rest at a distance of 0.250 m from its equilibrium position. What is the positionofthecartwhent=29.6s? T: $6 75/ A: 0.29m l/‘EO/Zf1’2é/j A)x=0.342m
B)x=0.318m USO _: 2/7 2
C)x=0.218m X('(’L A!“ [U ‘0 361/: __/_7: D)x=0.0460m 2 f/
m M): ONOMMSC—TEZM) @ 17) A meter stick with a mass of 89.5 g is being supported (initially horizontal) at the 50.0 cm mark 17) A i
by a pivot that is 1.00 cm above the center of mass of the meter stick. The moment of inertia of the stick about that point is 0.00746 kgmZ. What is the period of oscillation of this system? B) 2.89 s C) 2.41 s D) 2.01 s E) 4.02 s TLISLS a Pli‘thCa/ pen/d/UWL ‘E E 14/): mgl— or 7": 2F: 27 :I";
’— m L
<—»Q ”4 I «f 5‘
— 5.775 0.00746 mt
nd‘lL )orgféa‘f VAC/C T; 2 7T @,034Il<é)(7/?%)(oln) 18) The vertical displacement of a string is given by y(x,t) = (6.00 mm) cos[(3.25 m‘1)x — (7.22 s'l)t].
What is the amplitude of the wave? T
A) 12.0 mm A
B) 3.00 mm C 00 mm
D) 6.00 mm
one o the other choices is correct. 19) The total mechanical energy of a simple harmonic oscillator is
A zero when it reaches the maximum displacement.
3ch an erg T3 KahJ’ch/ov/
C) a minimum when it passes through e equilibrium point.
D) a maximum when it passes through the equilibrium point.
E) zero as it passes the equilibrium point. 20) A harmonic wave travels with a speed of 200 m/ s and has a wavelength of 0.800 In. What is the
frequency of the wave? A) 250 Hz B) 125 Hz C) 25.0 Hz D) 80.0 Hz E) 40.0 Hz 19) B 20) (2 ...
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