PHY2130 Fall 2012 Final Exam

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1 PHY130 Fall 01 Final Exam Fom A NAME: SIGNATURE: Instuctions 1. Put you books, notebooks, and cellphones on the floo unde you seat. You can keep you exam, calculato, and exta pens o pencils on you desk. Also place you OneCad on the desk.. All cellphones and othe devices, except fo calculato, should be poweed OFF and OFF the desktop. 3. Pint and sign whee indicated above. 4. A scoing sheet is povided with you exam. 5. Wite and bubble you name on the scoing sheet at the stat of the exam. 6. Bubble you answes to the multiple-choice poblems on the scoing sheet. 7. You may not leave the oom in the 10 minutes befoe the end of the exam. Once the exam ends, you must stop witing immediately and stand up at you seat. Put the scoing sheet inside the exam booklet and tun both in. Once all the exams have been collected, you will be allowed to leave the oom. 8. Answe all 35 multiple-choice poblems on this exam. Choose the best answe fo each. Questions 3 35 count fo cedit. 1

2 1. On the top ight of this page, what is the Fom you have? Fom A A. Fom A B. Fom B C. Fom C. Which class ae you in? A. Bowen, MWF 9:35 10:30 B. Conn, MWF 1:50 1:45 C. Paz, TuTh 6 7:0 D. Thaku, Oakland Cente 3. If the adius of a balloon shinks to 79% of its oiginal value, its new volume is what pecentage of oiginal volume? A. 49% B. 79% C. 9% D. 63% E. 89% 4. The gaph below shows the position y in m of a squiel unning up a flagpole but sliding back down. What is the velocity of the squiel at 5.5 s? A m/s B m/s C m/s D. 5.0 m/s E. 6.0 m/s y (m) t (s) 5. A ca taveling at 10.0 m/s acceleates at 3.0 m/s fo 4.00 s. How fa does it tavel duing this 4.00 s? A. 40 m B. 4 m C. 16 m D. 45 m E. 64 m

3 6. A ball olls East 4.4 m, bounces off a ock and olls Noth befoe coming to est.5 m fom the ock. If the tip takes.3 s, what is the magnitude of the aveage velocity of the ball? A. 5.1 m/s B.. m/s C. 3.0 m/s D. 1.9 m/s E. 11 m/s 7. A tennis ball is thown at 15.0 m/s at an angle of 35 up fom the hoizontal. What ae the velocity components of the ball 1.5 s late? The x axis is hoizontal in the diection of tavel and the y axis is up. A. v x = -1.3 m/s, v y = 6.1 m/s B. v x = -.4 m/s, v y = -6.1 m/s C. v x = 7.0 m/s, v y = 8.6 m/s D. v x = 1.3 m/s, v y = -6.1 m/s E. v x = 1.3 m/s, v y = 8.6 m/s 8. A 40 kg box is sliding down a amp angled at 15 down fom the hoizontal. The box is acceleating at 1.5 m/s down the amp. Ignoing ai esistance, what is the foce of fiction between the box and the amp? A N B N C N D N E. 39 N 9. Two blocks ae connected by a lightweight, flexible sting ove a massless fictionless pulley. If one block has a mass m = 15 kg and the othe a mass m 1 = 10 kg, find the acceleation of m 1, the 10 kg mass. A..0 m/s upwads B. 9.8 m/s upwads C. 4.9 m/s downwads D. 6.5 m/s downwads E. 3.3 m/s upwads 3

10. When a baseball is hit at an angle up fom the hoizontal (but not staight up), what can you say about its velocity and acceleation at the highest point of its motion? A.

4 10. When a baseball is hit at an angle up fom the hoizontal (but not staight up), what can you say about its velocity and acceleation at the highest point of its motion? A. The velocity is zeo and the acceleation is staight down B. The velocity is hoizontal and the acceleation is staight down C. The velocity and acceleation ae both zeo D. The velocity and acceleation ae both staight down E. The velocity is staight up and the acceleation is staight down 11. The oto is an amusement pak ide whee people stand against the inside of a cylinde. Once the cylinde is spinning fast enough, the floo dops out. The cylinde has a adius of 3.3 m. If the cylinde is to have a fequency of 0.50 Hz, what should be the minimum coefficient of fiction, such that the people don t fall out? A. µ = 0. B. µ = 0.1 C. µ = 0.4 D. µ = 0.3 E. µ = A space station is moving in a cicula obit aound the Eath. It makes one evolution in 90 minutes. How high above the Eath s suface is the space station? The mass of the Eath is kg and the adius of the Eath is m. A km B km C km D. 10 km E. 80 km 13. A lage cate is pulled along a hoizontal path at a constant speed by a cable that is inclined at an angle of 0 with espect to the hoizontal. The tension in the cable is N. The powe the cable supplies is W. How fa will the cate move in 10 seconds? A.. m B. 4. m C. 1 m D. 4.4 m E m 4

5 14. A potato sack of mass 0 kg, slides down a fictionless amp of length 3.0 m inclined at an angle θ with espect to the hoizontal. If the potato sack stats fom est, and at the edge of the amp its speed is 5.0 m/s, what is the angle θ? A. 3 B. 65 C. 5 D. 30 E. None of the above 15. A constant foce is applied fo the same duation of time on two objects. The mass of one object is twice as lage as the othe object. Which of the following is tue? A. Both objects will have the same momentum change, but the object with the lage mass will have the lage velocity change. B. Both objects will have the same momentum change, but the object with the smalle mass will have the lage velocity change. C. Both objects will have the same velocity change, but the object with the smalle mass will have the lage momentum change. D. Both objects will have the same velocity change, but the object with the lage mass will have the lage momentum change. E. None of the above. 16. Block A, with a mass of 00 g, is taveling noth on a fictionless suface with a speed of 5.0 m/s. Block B, with a mass of 300 g, tavels east on the same suface until it collides with A. Afte the collision, the blocks move off togethe with a velocity of.69 m/s at an angle of 48.0 to the noth of east. What was B s speed just befoe the collision? A. 1.0 m/s B. 3.0 m/s C. 5.0 m/s D..0 m/s E. 4.0 m/s 17. Fou equal.0-kg masses ae aanged at the cones of the squae. They ae connected by igid, massless ods of 0.50-m length. What toque must be applied to cause an angula acceleation of 0.90 ad/s about one side of the squae? A N m B. 1.8 N m C N m D N m E. 1. N m 5

6 18. A unifom disk with a mass of 1.0 kg and adius of 0 cm is otating on fictionless beaings with a otational speed of 10 ad/s when a clod of clay is dopped on a point 10 cm fom the cente of the disk, whee it sticks. If the new angula velocity of the disk is 8.7 ad/s, what is the mass of the clay? I disk = ½ MR. A kg B kg C kg D. 1. kg E kg 19. What is the buoyant foce on 1.00 kg of pine wood held completely submeged unde mecuy? Density of the pine wood is 350 kg/m 3 and that of mecuy is kg/m 3. A N upwad B. 0.5 N upwad C N upwad D. 6.1 N downwad E.. downwad 0. At the suface of the Eath the pessue is 105 kpa. What is the appoximate change in pessue in going 40 m above the suface? The density of the ai is 1.0 kg/m 3. A atm B Pa C Pa D N E Pa 1. A mass hanging vetically fom a sping and a simple pendulum both have a peiod of oscillation of 1 s on Eath. An astonaut takes the two devices to anothe planet whee the gavitational field is weake than that of Eath. Fo each of the two systems, which one of the following is tue? A. The peiod of the mass-sping system will emain the same but the oscillations of the pendulum will slow down B. The peiod of the mass-sping system will emain the same but the oscillations of the pendulum will become faste C. Thee will not be any change in the peiod of eithe D. The oscillations of both will slow down E. The oscillations of both will become faste 6

7 . The pong of a tuning fok moves back and foth when it is set into vibation. The distance the pong moves between its exteme positions is.40 mm. If the maximum acceleation of the pong is 8560 m/s, then what is the fequency of the tuning fok? Assume SHM. A. 765 Hz B. 880 Hz C. 356 Hz D Hz E. 565 Hz 3. The intensity of sunlight that eaches Eath's atmosphee is 1400 W/m. What is the intensity of sunlight that eaches a spaceship which is.5 times as fa away fom the Sun as the Eath? A. 560 W/m B W/m C. 700 W/m D. 4 W/m E W/m 4. A sting of length.0 m and linea mass density 5.0 mg/m vibates at a (fundamental) fequency of Hz. What is the speed of the tansvese sting waves? A. 340 m/s B. Cannot be detemined because the tension is unknown C m/s D. 900 m/s E. 333 m/s 5. A sound wave with an intensity level of 90.0 db is incident on an eadum of aea m. How much enegy is absobed by the eadum in 5.0 min? A. 0 J B. 18 µj C. 1.1 µj D. 5. µj E. 0.5 µj 6. A cetain pipe has esonant fequencies of 64 Hz, 440 Hz, and 616 Hz, with no othe esonant fequencies between these values. What is the fundamental fequency of this pipe? A. 88 Hz B. 64 Hz C. 78 Hz D. 10 Hz E. 56 Hz 7

8 7. A bubble of ideal gas with a volume of 1.00 cm 3 foms at the bottom of a lake that is 0.0 m deep. The tempeatue at the bottom of the lake is 10.0 C. The bubble ises to the suface whee the wate tempeatue is 5.0 C. Assume the bubble is small enough that its tempeatue always matches that of its suoundings. What is the volume of the bubble just as it eaches the suface of the wate? Ignoe suface tension. A. 1.4 cm 3 B. 4.4 cm 3 C..78 cm 3 D..00 cm 3 E cm 3 8. The eaction ate fo the pepupal development of male Dosophila is tempeatuedependent. The activation enegy fo this development is then J. A Dosophila is oiginally at C and it's tempeatue is inceasing. If the ate of development has inceased 3.5%, how much has its tempeatue inceased? A o C B o C C o C D o C E o C 9. Why does a helium weathe balloon expand as it ises into the ai? Assume that the tempeatue emains constant. A. The pessue outside the balloon inceases B. The numbe of helium atoms in the balloon inceases C. The pessue outside the balloon deceases D. The numbe of helium atoms in the balloon deceases E. Each helium atom undegoes a tansition to a lage fom 30. How much heat is equied to aise the body tempeatue of a 51.0 kg woman fom C to C? The specific heat fo human tissue is 3.50 kj/k. A. 15 kj B. 454 kj C. 07 kj D. 50 kj E. 350 kj 31. In a physics lab, a student accidentally dops a 5.0-g bass washe into an open Dewa of liquid nitogen at its boiling point of 77. K. How much liquid nitogen boils away as the washe cools fom 93 K to 77. K? The latent heat of vapoization fo nitogen is kj/kg. The specific heat of bass is kj/(kg K) A g B g C. 8.5 g D g E. 8.7 g 8

9 3. Two coppe bas ae placed in seies (end-to-end) between two tempeatue baths. The tempeatue of one of the heat baths is 104 o C. If the conductive heat flow is 0.16 W, what is the tempeatue of the othe, coole, heat bath? The themal conductivity of coppe is 401 W/(m K). The length of each ba is 0.10 m and the coss-sectional aea of each is 1.0 x 10-6 m. A. 10 o C B. 4 o C C. 5 o C D. 0 o C E. 60 o C 33. An ideal gas engine has an efficiency of 0.75 and uses gas fom a hot esevoi at a tempeatue of 6 K. What is the tempeatue of the cold esevoi to which it exhausts heat? A. 171 K B. 101 K C. 311 K D. 98 K E. 373 K 34. What is the change in entopy of 4.00 g of wate evapoating at 100 C? The latent heat of vapoization of wate is 56 kj/kg. A. -4. J/K B J/K C J/K D J/K E. +4. J/K 35. A themal system follows the cycle shown in the figue.(let V 1 = 0.00 m 3 and P 1 = 1atm) (a) How much net wok, W, is done on the system in one cycle?; (b) What is the heat flow, Q, into the system pe cycle? A. W = -18 kj; Q = 18 kj B. W = 18 kj; Q = -18 kj C. W = -100 kj; Q = 100 kj D. W = 100 kj; Q = -100 kj E. W = 18 kj; Q = 18 kj END OF EXAM 9

10 PHY 130 Fomulas Physical Constants g = 9.80 m (always down!) s G = m 3 /kg s Patm = kpa ρwate = 1000 kg/m 3 Boltzmann constant in Ideal Gas Law: kb = 1.38x10-3 J/K Univesal gas constant in Ideal Gas Law: R = 8.31 J / K mol 0ºC = K Avagado s Numbe: NA = 6.0 x 10 3 mol u = kg 1 cal = J Chapte 1 Intoduction Chapte Vectos and motion along a line o Displacement (change in position): Δ = f i. Δ o Aveage velocity: vav = Δ t Δv o Aveage acceleation: aav = Δ t o Constant acceleation equations: Δ vx = vfx vix = axt Chapte 3 ( ) 1 Δ x= x x = v + v Δ t Δ x= v Δ t+ a ( Δ t) 1 f i fx ix v v = a Δ x fx is x Two- dimensional motion sin opposite = cos hypotenuse adjacent = tan hypotenuse Chapte 4 Foce and Newton s Laws of Motion F o Newton s nd Law: a = o F = ma m Gm1m o The magnitude of the gavitational foce: F = o Weight :W = mg. o Static fiction: fs µ sn ix x opposite = adjacent 10

11 o Kinetic fiction: fk Chapte 5 = µ N k Cicula Motion o Angula displacement: Δ θ = θ f θi ; aveage angula velocity ωav o s = θ, 1 complete cicle = 1 evolution = π adians Δθ = Δ t o To elate linea to angula quantities: v = ω o o Chapte 6 o Acceleation in unifom cicula motion: v F = ma = m 1 f =, ω = πf T a v = = ω Wok and Enegy o Wok: W = FΔ cosθ (If F and ae along the x- axis then W = Fx Δ x). 1 o Tanslational kinetic enegy: = mv. Chapte 7 Ktans o The Wok- Kinetic Enegy Theoem : W total =Δ K o The gavitational potential enegy close to eath: U gav = mgy o Gavitational potential enegy eveywhee: Ugav = - Gm1m/ 1 o The potential enegy associated with a sping : U = kx. o The foce equied to pull on a sping: Fsping o Consevation of enegy : Einitial = Efinal. o Powe: ΔE P = = Δt Fv cosθ = kx Momentum, Impulse and Consevation of Momentum o Linea momentum: p= mv (Vecto). o Consevation of momentum p initial p o Δ p= F Δt. Chapte 8 Rotations, toques, and angula momentum o The otational kinetic enegy: K = ot 1 = final Iω sping 11

12 o Rotational inetia: I = m o Toque: τ = ± F = ± F = Fsinθ o Toque and angula acceleation α: τ = Iα, α lim Δω Δt 0 Δt o Angula momentum: L= Iω o Consevation of angula momentum: if τ = 0, Li = Lf o Rotational wok: W = τ Δθ Chapte 9 P = F/A ρ = m/v, S.G. = ρ/ρwate, P = Patm + ρgd, FB = ρflgvsub ΔV Δt = A v 1 1 = Av, P ρ gy1 + ρv1 = P + ρgy + ρv Viscous flow (Poiseuille): Viscous dag: FD = 6πηv ΔV Δt π ΔP / L = 8 η 4 Chapte 10 Suface Tension in a bubble: ΔP = γ/ F ΔL F Δx ΔV = Y = S Δ P = B A L A L V Simple Hamonic Motion (SHM) o The maximum displacement, velocity and acceleation in SHM: xm = A vm = ωa am = ω A o The equations of motion fo SHM: Assume x = A at t = 0: x = Acosωt, vx = - ωasinωt, ax = - ω Acosωt o The mechanical enegy fo SHM: E = ka = mv + kx mech SHM o The angula velocity fo a mass- sping system: ω = o The angula velocity fo a simple pendulum: sping ω = pendulum k m g L 1

13 Chapte 11 Waves Powe P o Wave intensity (fo an isotopic souce): I = = Aea 4π F o The speed of tansvese wave on a sting: v m sting = µ = µ L π π f o f, ω, λ ae elated! π f = ω; k = = λ v ω o The speed of a wave : v= λ f = k o The distance between two adjacent nodes is ½ λ (also the distance between two adjacent antinodes L v o Standing waves on a sting: λ n = ; fn = n (n=1,,3,...) n L Chapte 1 Sound o o v = B ρ Y v = v = TC m/s ρ o Pessue amplitude Vs displacement amplitude: p0 = ωvρs0 p0 o I = ρv I 1 o Sound intensity level: β = ( 10 db) log ; I W = m I0 o Standing sound wave in a pipe open at both ends: see fomulas fo standing waves on stings in Chapte 11 section o Standing sound wave in a pipe closed at one end: 4 L v λ n = ; fn = n (n=1,3,5,...) n 4L o Dopple shift: f o v v = v v o s f s Chapte 13 Tempeatue and the ideal gas o Tempeatue scales and convesions : T = T 73.15; T = (1.8 o F/ o C) T + 3 o F C F C 13

14 o Themal expansion: One dimensional (linea) Δ L= L ( αδ T) Two dimensional (aea) Δ A= A ( αδ T ) 0 0 Thee dimensional (volume)- - V V ( β T) Δ = Δ, β = 3α 0 o Ideal Gas Law: PV = NkBT; PV = nrt N o Kinetic theoy of gases: P= K ; t 3 V 3 1 Kt = kt = mv ms v ms = v, v ms = 3kT / m eaction ate e Mean fee path xms = Dt E a Λ = / kt πd 1 ( N / V ) Chapte 14 Heat Q Q o Heat capacity (C) and specific heat (c): C =, c = Δ T m Δ T Q o Specific heat of ideal gases: CV = (mola specific heat at constant n Δ T volume) 3 J / K Fo a monatomic ideal gas: C V = R = 1.5 mol Fo a diatomic ideal gas: 5 J / K C V = R = 0.8 mol o Phase tansitions and latent heat: Q = ml T o Themal conduction: P = κ A Δ, whee P is the ate of heat flow d o Stefan s Law P = eσat 4 o Wien Displacement Law: λmaxt = m K 14

15 Chapte 15 Themodynamics o The fist law of themodynamics: Δ U = Q+ W o Themodynamic pocesses: In geneal, the magnitude of the wok done is the total aea unde the PV cuve. 1. Constant pessue: W = PΔ V. Constant volume: W = 0; Δ U = Q 3. Constant tempeatue pocess fo an ideal gas: Δ U = 0 4. In an adiabatic pocess: Q= 0; Δ U = W. o The change in intenal enegy fo an ideal gas: Δ U = ncv Δ T o CP = CV + R Wnet o Efficiency e = QH o Enegy consevation fo heat engine: QH QC = Wnet TC o Canot efficiency fo heat engine: e = 1 TH Q o Entopy change of a system: Δ S = (= ΔSH + ΔSC fo two objects in T themal contact) 15

b) (5) What average force magnitude was applied by the students working together?

b) (5) What average force magnitude was applied by the students working together? Geneal Physics I Exam 3 - Chs. 7,8,9 - Momentum, Rotation, Equilibium Nov. 3, 2010 Name Rec. Inst. Rec. Time Fo full cedit, make you wok clea to the gade. Show fomulas used, essential steps, and esults