Phys 111 Exam 3 November 14, Name Section University ID

Transcription

1 Phys 111 Exam 3 November 14, 017 Name Section University ID Please fill in your computer answer sheet as follows: 1) In the NAME grid, fill in your last name, leave one blank space, then your first name. ) Write your ID number in the IDENTIFICATION NUMBER section of the sheet. 3) Write your recitation section number in the spaces K, L in the SPECIAL CODES section. Single digits should be preceded by a 0 (e.g. section 1 is written as 01). 4) Fill in the circles on the sheet corresponding to the letters or numbers of your name, ID and section with a # pencil. Note (a) Use g = 9.81 m/s if needed. (b) There are 0 multiple choice problems. (c).0 hour Exam (no one can leave before 9:15 PM). (d) Formula sheets are available (attached at the last two pages). (e) Record sheet is attached after the 0 exam problems. DO NOT USE CELL PHONES. Good Luck!!! 1

2 1. A 0.50-kg stone is attached to an ideal spring and undergoes simple harmonic oscillations with a period of s. What is the force constant (spring constant) of the spring? A).45 N/m B) 1.1 N/m C) 4.1 N/m D) 0.10 N/m E) N/m. The position of mass oscillating on a spring is given by the equation x = (1.4 cm) cos[t/(0.38s )]. What is the first time that the mass is at the position of x = 0? A) 0 s B) 0.07 s C) 0.19 s D) s E) s 3. The period of a simple pendulum that is 1.00 m long on another planet is What is the acceleration due to gravity on this planet if the mass of the pendulum bob is 1.5 kg? A) 14.3 m/s B) 13.3 m/s C) 15.7 m/s D) 17. m/s E) 1.5 m/s 4. The intensity of the waves from a point source at a distance d from the source is I. At what distance from the sources is the intensity equal to I? A) d/ B) d/ C) d/4 D) d/8 E) d 5. Transverse waves travel at in a string that is subjected to a tension of If the string is long, what is its mass? A) kg B) 0.16 kg C) kg D) kg E) kg

3 6. The frequency of the standing wave in a pipe (both ends open) shown in the right figure is 30 Hz. What is the fundamental frequency of the pipe? A) 50.5 Hz B) 101 Hz C) 151 Hz D) 5 Hz E) 303 Hz 7. You drop a stone down a well that is 9.5 m deep. How long is it before you hear the splash? The speed of sound in air is 343 m/s and air resistance is negligible. A) 1. s B) 1.3 s C) 1.4 s D) 1.5 s E) 1.6 s 8. The intensity level is 65 db at a distance 5.00 m from a barking dog. What would be a reasonable estimate for the intensity level if two identical dogs very close to each other were barking? You can ignore any interference effects. A) 65 db B) 68 db C) 130 db D) 136 db E) 35 db 9. Hearing the siren of an approaching fire truck, you pull over to side of the road and stop. As the truck approaches, you hear a tone of 460 Hz; as the truck recedes, you hear a tone of 410 Hz. How much time will it take to jet from your position to the fire 5.00 km away, assuming it maintains a constant speed? The speed of sound in air is 343 m/s. A) 63.5 s B) 17 s C) 508 s D) 5.5 s E) 54 s 3

4 10. Two in-phase loudspeakers are 3.00 m apart. They emit sound with a frequency of 490 Hz. A microphone is placed half-way between the speakers and then moved along the line joining the two speakers until the first point of constructive interference is found. At what distance from that midpoint is that first point? The speed of sound in air is 343 m/s. A) m B) m C) m D) m E) There is no point in that line where constructive interference occurs. 11. As shown in the figure, fluid fills a container having several sections. At which of the indicated points is the pressure greatest? A) A B) B C) C D) D E) The pressure is the same at each of the labeled points. 1. A cubical box 5.0 cm on each side is immersed in a fluid. The pressure at the top surface of the box is kpa and the pressure on the bottom surface is kpa. What is the density of the fluid? A) 1000 kg/m3 B) 1030 kg/m3 C) 1060 kg/m3 D) 1090 kg/m3 E) 110 kg/m3 13. A 4.0-kg cylinder of solid iron is supported by a string while submerged in water. What is the tension in the string? The density of iron is 7860 kg/m 3 and that of water is 1000 kg/m 3. A).5 N B) 0 N C) 4 N D) 34 N E) 40 N 4

5 14. A steel bridge is 1000 m long at -0 C in winter. What is the change in length when the temperature rises to 40 C in summer? The average coefficient of linear expansion of this steel is K-1. A) 0.33 m B) 0.66 m C) 0.55 m D) 0.44 m E) 0. m 15. Object 1 has three times the specific heat capacity and four times the mass of Object. The two objects are heated from the same initial temperature, T0, to the same final temperature Tf. During this process, if Object 1 absorbs heat Q, the amount of heat absorbed by Object will be A) 1Q. B) 6Q. C) Q. D) Q. E) Q. 16. Two metal rods are to be used to conduct heat from a region at 100 C to a region at 0 C as shown in the figure. The rods can be placed in parallel, as shown on the left, or in series, as on the right. When steady state flow is established, the heat conducted in the series arrangement is A) greater than the heat conducted with the rods in parallel. B) the same as the heat conducted with the rods in parallel. C) less than the heat conducted with the rods in parallel. 17. How much heat must be removed from 456 g of water at 5.0 C to change it into ice at C? The specific heat of ice is 090 J/kg K, the latent heat of fusion of water is J/kg, and the specific heat of water is 4186 J/kg K. A) 105 kj B) 153 kj C) 57.3 kj D) 47.7 kj E) 10 kj 5

6 kg person drinks a thick milkshake of 15,500 cal. How many stairs must this person climb to work off the shake? The height of the stair is 0.0 cm. (1 cal = J). A) 1760 stairs B) 41 stairs C) 35 stairs D) 4400 stairs E) 8800 stairs 19. In a section of horizontal pipe with a diameter of 4.00 cm the pressure is 95 kpa and water is flowing with a speed of 1.5 m/s. The pipe narrows to.00 cm and speeds up to 4.5 m/s. What is the pressure in the narrower region? (Density of water is 1000 kg/m 3 ) A) 95.0 kpa B) 43.7 kpa C) kpa D) 86.7 kpa E) 77.7 kpa 0. A 117 g lead ball is dropped from rest from a height of 7.6 m. The collision between the ball and the ground is totally inelastic. Assuming the ball s kinetic energy goes into heating the ball, find its change in temperature. The specific heat of lead is 18 J/(kg K) A) 1.17 C B) C C) 0.9 C D) C E).34 C 6

7 Record Sheet of Exam # 3, Physics 111, Fall 017 You may fill in this sheet with your choices and take it with you for comparison to the posted answers

8 Physics 111, Fall 017: Formula sheet Vectors: A Acos A Asin x y 1 x y tan Ay / Ax A A A Linear Motion: x x f xi v x / t a v / t v v0 at 1 1 x v0t a t v v0 a x x v0 v t v 0 Range; R sin g Forces: N Fnet mm 1 Fnet F1 F F3 Fi a Fg G i1 m r Weight W mg fk kn fs sn Fx kx Work and Energy: W ( F cos ) d KE mv / PE mgh P work / t Fd / t Fv Etot KE PE PE kx / Linear momentum and impulse: p mv Ft p I Ft p p 0 p f pi x m x / m cm i i i y m y / m cm i i i Uniform Circular Motion: v r / T a v / r c F c mv / r tan v / rg Rotational Kinematics: s/ r / t / t 0 t T / 1 0t t vt r t r 0 ac r Rotational Dynamics: rsinf L 0 Lf Li I miri I L / t L I KE R I / W Gravity: F Gm m r g 1 / G Nm kg / / g 1 PE U Gm m r KE mv / Oscillations about equilibrium: f F kx x Acos( t); vx Asin( t); ax Acos( t) T k L E KE PE mv kx ka T m g

9 Waves and Sound: F m P P v f v ; I T L A 4 r n log( AB) log( A) log( B); log( A/ B) log( A) log( B); log(10 ) n (10 db)log( I / I ); I 10 W / m Doppler Effect for moving source: f0 fs (-) source moving towards observer 1 vs / v v0 Doppler Effect for moving observer: f0 fs 1 (+) observer moving towards source v Constructive Interference: d1 d n; n 0,1,,3,... Destructive Interference: d1 d n ; n 1,3,5,... Standing waves on a string of length L = Standing waves in a column of air open at both ends of length L L v v n ; fn n ; n 1,,3,... n n L Standing waves in a column of air closed at one end of length L 4 L v v n ; fn n ; n 1,3,5,... n 4L Beat Frequency: fbeat f1 f n Fluids: M F 5 ; P ; Pgauge P Patm ; Patm N / m V A P P gh 1 F Vg Buoyant fluid m1 m Conversation of Mass : 1 A1 v1 A v t t 1 1 Bernoulli ' s Equation : P v gy P v gy Temperature and Heat: 5 TC TF 3 TK TC 73.15; L L0T ; V V0T ; Q mct Q ml ; Q ml ; Q / t kat / L; Q / t eat ; W( m K ) fusion f vaporization v Ideal Gases: 3 PV nrt Nk T; n N / N m / ( mass per mole); R 8.31 J( mol K); k J / K B A B NA molecules / mole; KEav ( mv ) av kbt; U nrt NkBT Thermodynamics: U Q W; W PV ; CV 3 R / ; CP 5 R / ; CP / CV 5/ 3 W Qh Qc Qc Tc Qh Qc e 1 1 ; COP ; Air Conditioner COP Qh Qh Qh Th W W Q Qh Qc S ; Stotal 0 T T T h c