PHYSICSBOWL March 29 April 14, 2017

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1 PHYSICSBOWL 2017 March 29 April 14, QUESTIONS 45 MINUTES The ponor of the 2017 PhyicBowl, including the American Aociation of Phyic Teacher, are providing ome of the prize to recognize outtanding high chool phyic tudent and their teacher through their performance on thi year contet. School compete in one of two diviion, each with nineteen region. o o Diviion 1 i for tudent taking phyic for the firt time (even if that firt coure i AP Phyic). Diviion 2 i for tudent taking a econd (or more) coure in phyic or anyone wanting a challenge. A chool' team core in each diviion i the um of the five highet tudent core in that diviion. A chool may compete in either or both diviion. INSTRUCTIONS Anwer heet: Write and bubble-in the following REQUIRED information on your anwer heet: Your Name Your Teacher AAPT Teacher code (given to you by your teacher only one code per chool!) Your Region (given to you by your teacher) Your Diviion (1 for firt-year phyic tudent, 2 for tudent in a 2 nd phyic coure or wanting a challenge) If thi information i not properly bubbled, you will be diqualified a your official core will be a zero. Your School CEEB code (given to you by your teacher), though not required, IS helpful in the event of a diqualification for identifying your chool. Your anwer heet will be machine graded. Be ure to ue a #2 pencil, fill the bubble completely, and make no tray mark on the anwer heet. Quetion: The tet i compoed of 50 quetion; however, tudent anwer only 40 quetion. Anwer hould be marked on the anwer heet next to the number correponding to the quetion number on the tet. Diviion 1 tudent will anwer only quetion Number on the anwer heet hould remain blank for all Diviion 1 tudent. Diviion 2 tudent will anwer only quetion Number 1 10 and on the anwer heet hould remain blank for all Diviion 2 tudent. Calculator: A hand-held calculator may be ued. Any memory mut be cleared of data and program. Calculator may not be hared. Formula and contant: Only the formula and contant provided with the contet may be ued. Time limit: 45 minute. Score: Your core i equal to the number of correct anwer (no deduction for incorrect anwer). If there are tie core, the entrie will be compared from the end of the tet forward until the tie i reolved. Thu, the anwer to the lat few quetion may be important in determining the winner and you hould conider them carefully. Good Luck! Copyright 2017, AAPT Diviion 1 & 2 1 Diviion 1 & 2

2 ATTENTION: All Diviion 1 tudent START HERE. All Diviion 2 tudent Begin on quetion # A cientit compute a peed a *** Treat g = m 2 for ALL quetion #1 # mm 3 μ. Which one of the following choice repreent thi ame peed? (A) 4 km (B) 4 nm (C) 4 m (D) 4 Gm (E) 4 pm 2. A mall object i releaed from ret and fall freely for 4.00 until reaching the ground. What wa the height above the ground from which the object wa releaed? (A) 10.0 m (B) 20.0 m (C) 40.0 m (D) 80.0 m (E) m 3. Which one of the following choice i a vector quantity? (A) average peed (B) kinetic energy (C) ma (D) time (E) acceleration 4. At which one of the following temperature doe water undergo a phae change into a olid at a preure of 1.0 atm? (A) 273 K (B) 0 (C) 32 (D) 100 (E) 0 K 5. Which one of the following choice i mot cloely aociated with the following obervation about an iolated object: The linear momentum of the object i contant.? (A) Huygen Principle (B) Kepler Firt Law (C) Hooke Law (D) Pacal Principle (E) Newton Firt Law 6. A ma connected to an ideal pring ocillate with a period T when it i releaed from ret at a poition A from equilibrium. Which one of the following choice correctly identifie the period of ocillation for the ma connected to the ame pring when it i releaed from ret at a poition 2A from equilibrium? (A) 1 T (B) 1 T (C) T (D) 2T (E) 4T 4 2 Diviion 1 only 2 Diviion 1 only

3 7. A traveling ine wave of frequency 3.0 Hz i known to move at 6.0 m on a tring. Which one of the following figure bet repreent what a one-meter ection of the tring could look like at an intant of time? (A) (B) (C) (D) (E) 8. A ma move along the x-axi following the poition v. time graph provided. During what time interval() doe the ma have an acceleration of 0 m 2? Time i repreented a t. (A) only from 0 < t < 3 (B) only at t = 5 (C) only from 7 < t < 10 (D) only from 0 < t < 3 and 7 < t < 10 (E) only from 0 < t < 3, t = 5, and 7 < t < A 4.00 kg object move to the right with peed 5.00 m. A 5.00 kg object move to the left with peed 3.00 m. After colliding, the 4.00 kg object move to the left with peed 1.00 m. What i the peed of the 5.00 kg object after the colliion? (A) 1.00 m (B) 1.80 m (C) 3.00 m (D) 4.11 m (E) 7.80 m 10. A 2000 kg car move over a hill at a contant peed of 12.0 m. At the very top of the hill, the hape of the road can be approximated a a circle with radiu 25 m, a indicated in the figure. Which one of the following choice bet repreent the magnitude of the upward force exerted by the road on the car? (A) 0 kn (B) 8.5 kn (C) 11.5 kn (D) 20.0 kn (E) 31.5 kn ATTENTION: All Diviion 1 tudent continue to quetion #40. Diviion 1 only 3 Diviion 1 only

4 All Diviion 2 tudent START HERE. Number 1 10 on your anwer heet hould be blank. Your firt anwer hould be for #11. *** Treat g = m 2 for ALL quetion #1 #50. Quetion refer to the following information: A 5.00 kg block lide with uniform acceleration on a horizontal urface for The block kinetic energy trictly decreae from 50.0 J to 20.0 J in thi time. 11. What i the average peed of the block during the motion decribed? (A) 7.00 m (B) 3.74 m (C) 3.65 m (D) 2.65 m (E) 2.58 m 12. Which one of the following choice bet repreent the magnitude of the block acceleration during the motion decribed? (A) 3.43 m 2 (B) 2.40 m 2 (C) 1.20 m 2 (D) m 2 (E) m According to currently accepted theory, dark matter make up approximately what percent of the Univere? (A) 5 % (B) 25 % (C) 50 % (D) 80 % (E) 99 % 14. A block i upended in the air at the end of a tring held by a peron. The peron pull on the tring uniformly accelerating the block upward for a hort time. During thi time, which one of the following choice correctly identifie the Newton Third Law pair force to the force of the tring on the block? (A) the gravitational force from the Earth on the block (B) the force from the tring on the peron (C) the force from the peron on the tring (D) the force from the block on the tring (E) the force from the peron on the block 15. Two block X and Y are in contact on a frictionle horizontal urface. A contant 35 N force i applied to the right onto block X. What i the magnitude of the force that block Y exert onto block X? (A) 35 N (B) 28 N (C) 25 N (D) 14 N (E) 10 N 16. Which one of the following choice bet repreent the type of electromagnetic wave aociated with a frequency of Hz? (A) AM radio (B) microwave (C) ultraviolet light (D) X ray (E) red light Diviion 1 & 2 4 Diviion 1 & 2

5 17. The following length are added together: L 1 = m, L 2 = m, L 3 = m, and L 4 = m. How many ignificant digit are in the reulting um? (A) 2 (B) 3 (C) 4 (D) 5 (E) A dik of radiu 75.0 cm make 3.5 revolution when coming to ret in What wa the initial angular peed of the dik? (A) 1.40 rad (B) 6.60 rad (C) 8.80 rad (D) 13.2 rad (E) 17.6 rad 19. An ideal ga at a temperature of 100 ha 3.0 mole of particle encloed in a 5.0 L container. Which one of the following choice bet repreent the preure of the ga? (A) Pa (B) Pa (C) Pa (D) Pa (E) Pa 20. An object appear green when ideal cyan light hine on it. If ideal yellow light were to hine on the object, which one of the following choice identifie the color() that the object could appear? (A) only red (B) only yellow (C) only green or black (D) only yellow or green (E) only yellow, green, or red 21. The change in linear momentum of an object i alway in the ame direction a the (A) velocity of the object. (B) diplacement of the object. (C) average peed of the object. (D) average velocity of the object. (E) average acceleration of the object. 22. A large wimming pool i filled with a liquid having a denity of kg m3. A peron want to ee what happen if he jump into the deep end of the pool (3.0 meter deep). Which one of the following choice correctly identifie what will happen to the peron? Aume that the peron doe not try to move their arm or leg until dicovering what happen after equilibrium i etablihed. (A) The peron will float with much more than 50% of their body volume above the liquid urface. (B) The peron will float with approximately 50% of their body volume above the liquid urface. (C) The peron will float with much le than 50% of their body volume above the liquid urface. (D) The peron will ink but remain off the bottom of the pool. (E) The peron will ink to the pool bottom. Diviion 1 & 2 5 Diviion 1 & 2

6 23. A 1500 kg car and a 6000 kg truck have a perfectly inelatic colliion on a treet. Which one of the following choice correctly identifie the object() that loe kinetic energy from the impact? (A) Neither object loe kinetic energy. (B) Only the car loe kinetic energy. (C) Only the truck loe kinetic energy. (D) Both the car and truck loe kinetic energy. (E) The anwer cannot be determined without more information. 24. What condition mut be met for the angular momentum of a ytem to be contant? (A) The mechanical energy i contant. (B) There i no net external force acting on the ytem. (C) The ytem i in tatic equilibrium. (D) There i no net external torque acting on the ytem. (E) Only the gravitational force i acting on the ytem. 25. A box lide with uniform acceleration up an incline. The box ha an initial peed of 9.0 m and rie vertically 2.60 m before coming to ret. If the angle of the incline i 30, what i the coefficient of kinetic friction between the box and the incline? (A) (B) (C) (D) (E) A 4.00 kg ma i in uniform circular motion a hown in the figure. The tring to which the ma i attached ha a length of L = 3.00 m and form an angle of θ = 50.0 with the vertical. What i the peed of the ma? (A) 5.23 m (B) 5.54 m (C) 5.98 m (D) 6.62 m (E) 6.90 m 27. A 2.0 kg ma move at 10.0 m when it ha a colliion in pace. The ma peed wa unchanged, but the direction of it velocity wa altered by 80. If the colliion lated 0.25, what wa the magnitude of the average force exerted on the ma? (A) 0 N (B) 54.7 N (C) N (D) N (E) N 28. A hipment of part i labeled in unit of ohm econd. Which one of the following choice repreent an equivalent unit? (A) henry (B) farad (C) joule (D) volt (E) weber Diviion 1 & 2 6 Diviion 1 & 2

7 29. Two lightbulb (X and Y) are connected in erie to a battery. Bulb X i brighter than bulb Y. Aume all circuit element are ideal. If bulb X and Y are connected in parallel with each other to the ame battery, which one of the following choice bet repreent what i oberved? Bulb X Bulb Y Comparion (A) Brighten Brighten Bulb X remain brighter than bulb Y (B) Brighten No Change Bulb X remain brighter than bulb Y (C) Dim Brighten Bulb X remain brighter than bulb Y (D) Dim Brighten Bulb Y now i brighter than bulb X (E) Brighten Brighten Bulb Y now i brighter than bulb X 30. Two car, P and Q, each tart from ret at the origin and will move along the x-axi. The acceleration v. time graph for each car i hown. Which one of the following choice correctly identifie the relationhip for both the peed (v P and v Q ) and the poition (x P and x Q ) of the car at time T? peed poition (A) v P = v Q x P > x Q (B) v P > v Q x P > x Q (C) v P = v Q x P = x Q (D) v P < v Q x P < x Q (E) v P = v Q x P < x Q 31. A olid cylinder roll without lipping on a rough inclined plane. Which one of the following choice bet repreent the type and direction of friction (if any) acting on the cylinder a it roll up the incline? (A) Static friction directed up the incline (B) Kinetic friction directed up the incline (C) There i no friction (D) Kinetic friction directed down the incline (E) Static friction directed down the incline 32. A projectile i launched at an angle of 40 above the horizontal with a peed of 30 m. How much time pae before the poition of the projectile make an angle of 20 above the horizontal from the original launch point? (A) 3.02 (B) 2.38 (C) 2.18 (D) 1.93 (E) 1.64 Diviion 1 & 2 7 Diviion 1 & 2

8 33. Two long wire are fixed in pace o that the conventional current in the left wire (2 A) come out of the plane of the page and the conventional current in the right wire (3 A) goe into the plane of the page. In which Region() i there a place on the x-axi (aide from infinity) at which the magnetic field i equal to zero from thee current? (A) Only in Region I (B) In both Region I and II (C) Only in Region II (D) In both Region I and III (E) In both Region II and III 34. A 9.20 m long uniform plank ret on a frictionle ice pond. A 52 kg box ret on the plank left end while a 71 kg peron tand at the plank right end. After the peron walk to the left on the plank and tand at the ame location a the box, the plank ha lid 3.84 m to the right relative to the pond hore. Which one of the following choice bet repreent the ma of the plank? (A) 123 kg (B) 61.5 kg (C) 47.1 kg (D) 36.5 kg (E) 31.2 kg 35. A metal bar i moving to the left acro a et of frictionle conducting rail a een in the figure. Throughout the region between the rail, there i a uniform magnetic field directed into the plane of the page. The reitor labeled X and Y are identical. Which one of the following choice correctly indicate the direction of the conventional current in the reitor and the relation between the magnitude of the current through each reitor at the intant hown? Current through X Current through Y Relation between Current (I X, I Y ) (A) Up the plane of the page Up the plane of the page I X > I Y (B) Up the plane of the page Up the plane of the page I X = I Y (C) Up the plane of the page Down the plane of the page I X > I Y (D) Down the plane of the page Down the plane of the page I X = I Y (E) Down the plane of the page Down the plane of the page I X > I Y 36. A cientit perform an experiment in which he determine the hortet length of a ga column needed to create reonance for a vibrating tuning fork over a tube cloed at one end. She plot the ga column length againt the invere of the frequency for a et of tuning fork and find that he ha a traight line fit through the data. Repreenting the lope of the line a m, which one of the following choice correctly identifie the peed of wave through the ga in the experiment? (A) 1 m (B) m (C) 2m (D) 4 m (E) 4m 4 3 Diviion 1 & 2 8 Diviion 1 & 2

9 37. Which one of the following choice bet approximate the magnitude of the Earth angular momentum (expreed in bae MKS unit) aociated with it orbit around the Sun? (A) (B) (C) (D) (E) A mall 2.0 kg block ret at the bottom of a bucket. The bucket i pun in a vertical circle of radiu L by a rope. When the bucket reache the highet point in it motion, it move jut fat enough for the block to remain in place in the bucket. When the bucket i at an angle θ = 30 from the vertical, a een in the figure, what i the magnitude of the normal force (perpendicular to the urface) provided by the bucket onto the block? Note that the direction of the gravitational field i indicated in the diagram by g and that the block doe not touch any ide of the bucket aide from the bottom of it. (A) 8.0 N (B) 10.0 N (C) 15.4 N (D) 18.7 N (E) 37.3 N 39. A point wave ource travel along the x-axi at contant peed v. Stationary oberver on the x-axi meaure the wavelength of the wave that they receive. The ratio of the wavelength meaured at a location behind the ource to the wavelength meaured at a location in front of the ource i If the wave peed i v, what i the ource peed v? (A) 1 5 v (B) 1 4 v (C) 1 3 v (D) 1 2 v (E) 2 3 v 40. A mall object of ma M i releaed from ret at the top of a frictionle incline. The incline ha a ma M and make an angle θ with the horizontal. The incline remain at ret on a table a the mall object lide. During the lide, what i the magnitude of the normal force from the table on the incline? (A) 2Mg (1 tan θ) (B) 2Mg (1 in θ) (C) 2Mg (D) Mg (2 in 2 θ) (E) Mg (2 in θ) IMPORTANT: All Diviion 1 tudent STOP HERE. Your lat anwer hould be for #40. Number hould remain blank for Diviion 1 tudent. All Diviion 2 tudent continue to Quetion Diviion 1 & 2 9 Diviion 1 & 2

10 ATTENTION: All Diviion 1 tudent STOP HERE. All Diviion 2 tudent continue to quetion # Pure red light hine through a diffraction grating of 1200 line cm and produce an interference pattern on a creen a ditance 5.0 m away. Which one of the following choice bet repreent the ditance between the firt and third principal bright pot on the creen? (A) 0.02 m (B) 0.10 m (C) 1.0 m (D) 2.0 m (E) 4.0 m 42. A long uniform rod, pivoted at one end affixed to the ground, i in tatic equilibrium A horizontal rope act 75% of the way up the rod while a vertical rope act at the far end. The magnitude of each rope force i the ame a the gravitational force acting on the rod. What i the value of the angle θ in the figure? (A) 18.4 (B) 21.8 (C) 33.7 (D) 36.9 (E) A emi-circle ha radiu R, total charge Q, and a charge per unit length given a λ = λ 0 co θ with θ defined in the figure and λ 0 a poitive contant. Which one of the following choice give the electric field trength at the point labeled P? (A) 0 (B) 2k eλ 0 (C) k eqλ 0 R 2 R (D) 2k eq λ 0 (E) k eλ 0 π πr 2 2R 44. A ball i launched vertically upward. The vertical poition of the ball 0.70 after releae i the ame a it vertical poition 4.10 after it releae. At what time i the object firt at a vertical poition that i one-half of the maximum height it obtain during it flight? (A) 0.35 (B) 0.70 (C) 0.85 (D) 1.20 (E) Which one of the following magnification cannot be produced uing a ingle converging len? (A) 1 2 (B) 2 (C) 1 2 (D) 1 (E) 2 Diviion 2 only 10 Diviion 2 only

11 46. Two copper phere, X and Y, with different radii (R X > R Y ) and equal exce charge +Q, are placed apart from each other. A cientit uing inulating glove connect the phere with a copper wire. Which one of the following choice bet decribe what happen after the connection i made? (A) There i a net movement of electron from phere Y to phere X until the electric field jut outide the urface of each phere ha the ame magnitude. (B) There i a net movement of electron from phere Y to phere X until the electric potential jut outide the urface of each phere ha the ame magnitude. (C) There i a net movement of electron from phere X to phere Y until the electric field jut outide the urface of each phere ha the ame magnitude. (D) There i a net movement of electron from phere X to phere Y until the electric potential jut outide the urface of each phere ha the ame magnitude. (E) There i no net movement of electron from one phere to the other becaue the phere already have equal charge. 47. Once the circuit hown reache equilibrium, what i the magnitude of the potential difference acro the capacitor? (A) 0 ξ (B) 1 9 ξ (C) 2 9 ξ (D) 5 9 ξ (E) 2 3 ξ 48. In the binary tar ytem hown, the two tar follow circular orbit about the ytem center of ma. The tar are eparated by a ditance D that i large compared to their ize and are ubject only to their mutual gravitational attraction. The orbital period of the tar of ma M i T. Which one of the following choice repreent the total ma of the binary tar ytem? (A) π2 D 3 5GT 2 (B) 4π2 D 3 5GT 2 (C) 4π2 D 3 GT 2 (D) 16π2 D 3 (E) 25π2 D 3 5GT 2 4GT Two identical particle travel to the right. The particle traveling at m collide with and tick to the other particle traveling at m. Which one of the following choice bet repreent the peed of the reulting object after colliion? (A) m (B) m (C) m (D) m (E) m 50. A monatomic ideal ga undergoe the reverible cyclic proce (ABCA) hown in the PV diagram. Proce A B i adiabatic. What i the efficiency of thi engine? (A) 0.15 (B) 0.22 (C) 0.33 (D) 0.47 (E) 0.67 IMPORTANT: All Diviion 2 tudent STOP HERE. Your lat anwer hould be for #50. Diviion 2 only 11 Diviion 2 only