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Unformatted text preview: Name (please print):
Signature: Student number: (J T: O {\J S“ FACULTY OF PURE AND APPLIED SCIENCE
YORK UNIVERSITY
DEPARTMENT OF PHYSICS AND ASTRONOMY PHYS 1420 06 — Physics
F/W 0910 Mid—term examination
Instructions: 1. Print your name and student number on this page in the upper left corner.
2. Check that your exam contains 7 questions. 3. T he total number of marks is 80. 4. Calculators are allowed as aid. 5. Answer all questions in the space provided on this test paper. 6. Formulae are provided on the last page of this paper. l. (22 marks, 2 marks for each question). Answer the following eleven multiple choice questions. Circle the correct answer in the answer table provided below. E
EM!
#5 a. Figure below gives the velocity of a particle moving along an x axis. At which of the Six
numbered points is the magnitude of acceleration largest? b. A j uggler throws a ball straight up in the air. Aﬂer the ball leaves his hand and while it is in
the air, which statement is true? 1. The velocity of the ball is always in the same direction as its acceleration
2. The velocity of the ball is never in the same direction as its acceleration 3. The acceleration of the ball is zero
The velocity of the ball is opposite its acceleration on the way up.
The velocity of the ball is in the same direction as its acceleration on the way down. c. A man, with his arms at his sides, is spinning on a light frictionless stool. When he extends his
arms: 1. his angular speed increases
2. his angular speed remains the same
3. his rotational kinetic energy increases
4. his mement of inertia decreases
@his angular momentum remains the same d. The mass of a hypothetical planet is 1/1000 that of Earth and its radius is 1/4 that of Earth. If a
person weighs 600 N on earth, what would he weigh on this planet? 1. 2.4N
2. 4.8N
(99.61%
4. 96N
5. 600N e. Radioactive nuclei emit spontaneously some particles. In this process the following quantity or
quantities are conserved. l. kinetic energy @nomentum 3. potential energy
4. momentum and kinetic energy
5. momentum and potential energy f. A 0.2 kg stone is attached to a string and swung in a circle of radius 0.6 In on a horizontal and
frictionless surface. If the stone makes 150 revolutions per minute, the tension on the string is 1.0.03 N 2. 0.2N ..
3. 0.9N F“ ma a
4.1.96N 1 ., ‘2 2’23!) {HM—a
F:ﬁ.2 £31125: ( " ——“
@3ON M nu I 12.9..) 60$ g. Two points are located on a rigid wheel that is rotating with an increasing angular velocity
about a ﬁxed axis. Point A is located on a rim of the wheel and point B is halfway between the
rim and the axis. Which of the following statements is true concerning this situation? 1. Both points have the same centripetal acceleration. 2. Both points have the same tangential acceleration. 3. The angular velocity of A is greater than that of B. The angular velocity of A is smaller than that of B.
oth points have the same instantaneous angular velocity. i. A baseball (mass 0.2 kg) traveling at 50 rn/s is struck by a bat and goes straight back to the
pitcher at the same speed. The hat was in contact with the ball for 0.1 s. The average force exerted by the hat on the ball is ‘lﬁlOON
2.150N
200N Fr, 91:: ._ W”): E
.300N ' at: ’ {36— «H
5.1000N
2 02 50W; j . A man whose weight is 800 N is standing upright. How much is his femur (thighbone)
shortened compared when he is lying down? Assume that the average crosssectional area 0 f the
femur is A = 8.0 crnz, and its length is L = 43.0 cm. Young’s modulus in compression is Y = 9.¢x109 N/mz. (90.0023 cm 2. 0.046 cm
3. 0.23 cm
4. 0.46 cm
5. 0.011 cm k. Water is pumped through the hose shown below, from a lower level to an upper level.
Compared to the water at point 1, the water at point 2: 1. has greater speed and greater pressure
has greater speed and less pressure 3. has less speed and greater pressure 4. has less speed and greater pressure 5. has greater speed and the same pressure. upper level
:2 ‘ 1(— lower level 2, (8 marks)
A mass, m = 0.80 kg, is attached to one end of a spring and the system is set into simple harmonic motion. The position x of the object as a ﬁmction of time is given by the following
equation; x = 0.15eos(2.30t), where t is in seconds and x is in meters. The mass of the spring is negligible. a. Determine the Spring constant.
we, ) wLZtBO ’12.. ' U
kzwzm —_ 2_30H1)a(@_fdfagj: 9.23 /m b. Determine the kinetic energy and the spring potential energy at t = 2.0 s. ’PEst i“ 142:?“
X{&=2.og): 0.1.x” Cos[(13.9 g)(2.o,)] .— Q anew m = 5(4. 2% gywpremji sterrdi‘]
I<E= j [a #11912: (a KL: 2LI¢( rﬁ—xl} I ijijﬁ/jZ—(Qrsjz— (ﬂamerﬂ3QDQﬁljr
0R . r
KEstmua :jafﬁﬁmﬂwf/f ari’prgo/‘mtﬂ'ﬂwj (241}: 09.0 ‘( ’12]. c. What is the Velocity of the mass att = 2.0 s? V=gé : _<OIU~)[2. so) 5"” [€2.3oj(2.u}]: — 0,39 “4!! @ (LCth couscgumrrou 5F REE(MCAC. EMEQGY
2.
2.
i 24 1‘ ikar 2cm” , _ a ;
_ ma _ Mow Uh” 6&1 '— er c9. d’o tr
U“.  0. 2. ‘1 “'15.
e. What is the acce1eration of the mass at t i 2.0 S? U 3
Ct: 5’2? = —{WJ‘JKZsoizcoSCCZSOMZUJJ: 00"? “VIZ 3. (10 marks) A ﬂea jumps from the ground with an initial Speed of 4.0 m/s directed at an angle 80 = 60.00
above the horizontal. ' a. What is the maximmn height reached by the ﬂea?
ﬁrm: 6 +5 4?{
0‘93 : 02: ﬁrhéd°r/é0“?§/ £2.52)": 3.46%}
4;, =44” ‘e’frz {)7 t: a {If ffzﬂﬂafk' #672987} a :: 314% léléaj"; 2 aw r/éég Waﬂgj ~74 fﬂéapfz/éz» art/2 54/” 5 a 57m b. How far does it travel horizontally?
A K “L 001* '6
aw : oz; reggo ° :(540 Mr!) (wjécf: go ‘73 f"; 265931—5): (221:); A Ktﬂcd ‘t‘érj/a. 9:95): Aéw. 4. ( 10 marks) How much force must the biceps muscle exert when a 5.0 kg ball is held in the hand with the amt
horizontal like in ﬁgure (a), and when the arm is at 450 angle as shown in ﬁgure (b)? The biceps muscle is connected to the forearm by a tendon attached 5.0 cm from the elbow joint.
Assume that the mass of forearm and hand together is 2.0 kg and location of their center of
gravity (CG) is shown in ﬁgure (a). T/ﬂfmUG— 7W5 Fame? 4’7— W5 ‘7‘”“7 f= dd 23‘70 {50km  52.. FM ( a. or...) aﬂwajﬁg Flaw. (Iajwﬂoég/ﬂﬂﬂz E _ ..
3 _ / 5‘2
WIS cmat
(a) Lmﬁﬂn FA : 4wan ; 2;
is
it
i?
. 1;
.  ll
. it (b) 5. (10 marks) A sledge loaded with bricks has a total mass of 18.0 kg and is pulled by a rope inclined at 30.00
abOVe the horizontal. The tension in the rope is 80.0 N. The sledge moves a distance of 20.0 m
on a horizontal Surface. The coefﬁcient of kinetic friction between the sledge and surface is 0.20. a. Draw the freerbody force diagram for the sledge. Um T
b. What is the kinetic force of friction acting on the sledge? a at» 20 7D F—‘ruo )Ui 5:2;ch
M473“. 3d “Mfr—“K3 ff: mf r 73 in $0 Zﬂdly/fffj ~ﬂ’LaOKJ/irm Zoo p t; [362910
J2 :(@&2) (/35. 9,0}: .223 A» c. Determine the work done by the tension. A] t wfjovgﬂﬂ,e1p//M&M/Mgaai d. Detennine the work done by the force of friction. it,» x: 71L Ax age)“: a.— (‘271—"3M (wee): “546947 e. Use the work—kinetic energy theorem to determine the speed of the sledge at the end of the
20.0 rn displacement. Assume that the sledge starts from rest. Me Al: , atzéeufa—gimcgé 03:9 W tech + UN «— ka : {3&7607f01‘0f—5F45‘CE/ he 6. (10 marks). A 12.0 kg object is attached to a cord that is wrapped around a solid disk of radius r = 10.0 cm,
as shown below. The acceleratiori of the object down the frictionless incline is 2.00 m/sz. Assume that the axle of the wheel to be frictionless. a. Draw the free bodyforce diagram for the object and the disk b. Determine the tension in the cord.
c. Determine the moment of inertia of the Wheel ‘
d. Determine the angular speed of the wheel 2.00 s after it begins rotating, starting from rest mffm 320°~ T wad/Ia, 7» {Zoe/[KWE’EJJMW " 1° W 7‘? 4WD 7. (10 marks). A 10.0 kg block of metal is suspended from a scale and immersed in water, as shown below. The
dimensions of the block are 12.0 cm X101) cm x100 cm. The 12.00111 dimension is vertical, and the top of the block is 5.0 cm below the sorface of water. The atmospheric pressure
Po =1.01x105 Pa. a. Determine the buoyant force on the block of metal. éewrj 5: Jim lame j WféWWV/Mmll W)
F; : //.’cf’K/ b. What is the reading of the spring scale?
'5 2 O T‘T pgch‘frc—D 7— : p.439 5;“ :ﬂueod/cp M Mia/U '1 £2 ,0. c. What is the absolute pressure at the level of the top of the block and at the level of the bottom
of the block? 7;? 1 asjoyérop —— (visitor/2t. + mggj/Fiff‘U/ﬁaefgij 7:39“: K(Or/)d.. lime as 2. e longde '1 gamearm I: ﬁt) éﬁ'J/ffg/fko (re/2 M2 «fade
d. What are the forces exerted by the water on he to I I ' I3 and the bottom of the bl k?
differences between these two forces equal to 1the b 00 Is the uoyant force? 7 . r g
257;}: Ergo/i : Ab/N’Mo Mfg? loo/4,}: AH)?qu
asmh '2 E;ng E/KOZQJMOchgj/QJQQAJZ: @2129 fUZ‘T}IU»— {la/FLSHU :— M‘feb I:ng \ THE END ...
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 Spring '09
 WIJNGAARDEN
 Physics, Force, Friction, Kinetic Energy, Angular velocity

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