Physics 1135 Version A

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1 Physics 1135 Version A Spring 2017 Answer Sheet Solution Rec Sec E ini-test First Name: & Final Exam Remove this page from your exam when you begin. Write clearly in the space provided on this Answer Sheet the letter which you believe to be the best answer to each question. ONLY THIS ANSWER SHEET will be looked at for scoring. ake sure your chosen answers are on it and do not leave any answer space blank. NO ELECTRONIC DEVICES are permitted during the test. Neither calculators nor notes may be used. E ini-test Score = 50 Final-Exam Score = 200 ini-test Responses (10 pts each) Final-Exam Responses (10 pts each) Em - 1) A 1) B 11) D Em - 2) B 2) D 12) D Em - 3) D 3) C 13) C Em - 4) C 4) A 14) A Em - 5) C 5) B 15) B 6) B 16) B 7) C 17) D 8) C 18) B 9) A 19) A 10) B 20) D Physics 1135 Spring 2017 Final Exam A 0

2 End-aterial ini Test Em-1. You drop your phone, which is ringing with frequency f, from the top of a cliff. What is the frequency you will last hear just before the phone meets its untimely demise when it hits the ground with speed V? The speed of sound is v. A) f/(1 + V/v) B) f/(1 V/v) C) f(1 + V/v) D) f(1 V/v) Em-2. A transverse traveling wave on a string is described by the equation y(x, t) = A sin(kx ωt). If one knows that the wave speed is equal to the maximum speed experienced by a bit of matter in the string, one can conclude that: A) k = ω B) A = 1/k C) A = ω/k D) A = k 2 + ω 2 Em-3. A rod of uniform cross-section is obtained by joining two equal-length segments of two different materials. The left half of the rod has thermal conductivity k 1, and the right half has thermal conductivity k 2. The left end of the rod is at temperature TH, and the right end is at temperature TC. When steady state is reached, the temperature at the boundary between the materials equals A) (T H + T c )/2 B) (k 1 T H + k 2 T C )/(k 1 k 2 ) C) k 1 k 2 (T H + T C )/(k 1 + k 2 ) D) (k 1 T H + k 2 T C )/(k 1 + k 2 ) Em-4. Considering only the points A, B, C, D in the PV diagram at the right, the ratio between the highest and the lowest temperatures is A) 2 B) 3 C) 6 D) 3/2 2P 0 A B Em-5. A monatomic gas is undergoing the process A-C in the PV diagram at the right. The amount of heat flowing into the gas equals P 0 D C A) 3 2 p 0V 0 B) 3p 0 V 0 C) 9 2 p 0V 0 D) 11 2 p 0V 0 V 0 3V 0 Physics 1135 Spring 2017 Final Exam A 1

3 Final Exam 1. A ball is launched from ground level with speed V at angle θ above the horizontal and hits the level ground after covering a horizontal distance D. Ignore air resistance. The time it takes the ball to hit the ground is equal to A) D/V B) D/(Vcos θ) C) (2gD) ½ D) (2DVcos θ) ½ 2. A stone, a feather and a piece of cork are thrown from the same height above the ground vertically up with the same initial speed. If you ignore air resistance, which object will hit the ground first? A) The piece of cork B) The stone C) The feather D) All three will arrive simultaneously 3. A satellite is moving with constant speed in a circular orbit around the Earth. Which of the following is true about the satellite s acceleration? A) It is equal to zero B) Centripetal acceleration is zero, while tangential acceleration is not C) Centripetal acceleration is non-zero, but the tangential acceleration is zero D) Both centripetal acceleration and tangential accelerations are non-zero 4. A toy car is moving in vertical circles inside a hollow cylinder of radius R. What is the smallest speed at the top of the circle for the car not to fall? A) gr B) 0 C) 2gR D) The car will fall at any velocity 5. A parachutist is descending vertically at constant speed. What is true about the air resistance force? A) It is a reaction force to the gravitational force acting on parachutist B) It is equal in magnitude and opposite in direction to the gravitational force acting on parachutist C) It is equal to zero D) None of the above 6. An object of mass m is on a level rough surface with a coefficient of static friction and is subject to a constant force P acting at an angle below the horizontal. The object is at rest. The magnitude of the friction force is: A) Psin B) Pcos C) (mg + Psin ) D) (mg+pcos ) 7. A block of mass m is on an incline that makes an angle with the horizontal. The minimum coefficient of friction for a block to remain at rest is: A) 0 B) cot( ) C) tan( ) D) The block will move regardless of the value of the coefficient of friction. Physics 1135 Spring 2017 Final Exam A 2

4 8. A truck is moving with constant acceleration a over a distance d along a flat surface. A crate of mass is resting on the truck s rough bed. The coefficient of static friction between crate and truck bed is μ. The work done by the frictional force on the crate over this distance is A) gd B) - gd C) ad D) ad 9. The potential energy of a particle varies with position as U(x,y) = y(ax 2 + bx). The x-component of the corresponding force is Fx = A) -y(2ax + b) B) -2ax b C) y(2ax + b) D) 2ax + b 10. A rock of mass m is shot straight up from the surface of Earth (with mass and radius R) with some initial speed. If the speed of the rock is to never drop below one half of the initial speed at any height above the surface, the initial speed must be at least A) 2G R B) 8G 3R C) 4G R D) 8G 3R The total linear momentum of a system of particles is conserved if and only if A) no external forces are acting on the system B) the internal forces add up to 0 C) only conservative forces are acting on the system D) the external forces add up to A pumpkin of mass, initially at rest, explodes into two fragments. The lighter fragment has one third of the initial mass of the pumpkin. The ratio between the speed of the lighter fragment and the speed of the heavier fragment is A) 1 B) ½ C) 3 D) A wrench dropped by a crew working on a tower falls and crashes into the surface of Earth. The magnitude of the change of the momentum of Earth resulting from this crash is A) small compared to the wrench s momentum change B) large compared to the wrench s momentum change C) equal to the wrench s momentum change D) zero 14. A ball is floating in water such that ⅓ of its volume is above the water surface. The ratio between the density of the ball and the density of water is A) ⅔ B) ⅓ C) 3 /2 D) A hoop and a solid uniform ball have the same radius. The hoop has a moment of inertia about its center of mass Ihoop = R 2 and the ball has a moment of inertia about its center of mass Iball = 2 /5 mr 2. Both are released from rest at the top of an incline at the same time and roll without slipping. Which will reach the bottom of the incline first? A) hoop B) ball C) they arrive at same time D) whichever has the greater mass Physics 1135 Spring 2017 Final Exam A 3

5 16. An object is undergoing simple harmonic oscillations with amplitude A. At what displacement from the equilibrium position does its kinetic energy equal three times its potential energy? A) ⅓ A B) ½ A C) ⅔ A D) A P 17. A rod of mass and length 2L hung from a pivot P at one end performs small oscillations in a vertical plane. What is the period of this pendulum s swing? (A rod of mass m and length D has a moment of inertia about its center of mass Icm = 1 /12 md 2 and a moment of inertia about one end I = ⅓ md 2.) 2L A) 2π L g B) 2π 2L g C) 2π L 6g D) 4π L 3g 18. A boy of mass is standing halfway between the center and the rim of a merry-go-round in the shape of a solid disk of mass 3 and radius R that is rotating about a vertical axis with angular speed ω. The moment of inertia of a disk of mass m and radius r about its center of mass is ½mr 2. Treating the boy as a point mass, the total angular momentum magnitude of the boy-disk system is A) ¾ R 2 ω B) 7 /4 R 2 ω C) 2 R 2 ω D) 5 /2 R 2 ω 19. A uniform stick of mass and length L is rotating about the pivot point P at its upper end. At the instant the stick is positioned vertically, a ball of mass 2, moving with speed 2V, strikes the lower end of the stick. After the collision, the stick is motionless and the ball rebounds with Initial speed V. The moment of inertia of the stick about P is ⅓L 2. The angular speed of the stick immediately before the collision was: 2 2V P Final ω= 0 V L A) 18 V/L B) 6 V/L C) 15 VL D) 6 VL 20. A stationary horizontal bar of mass and length L is attached to a wall at its left end and supported by a cable at its right end, as shown in the figure. The cable makes an angle θ with respect to the horizontal. A block with the same mass as the bar is hanging from the right end. The magnitude of the tension in the cable is T? θ A) 2g/sin θ B) 3gL C) 3g/(2cos θ) D) 3g/(2sin θ) L The Physics 1135 Instructors wish you a great summer! Physics 1135 Spring 2017 Final Exam A 4

Use a BLOCK letter to answer each question: A, B, C, or D (not lower case such a b or script such as D)

Use a BLOCK letter to answer each question: A, B, C, or D (not lower case such a b or script such as D) Physics 23 Spring 212 Answer Sheet Print LAST Name: Rec Sec Letter EM Mini-Test First Name: Recitation Instructor & Final Exam Student ID: Gently remove this page from your exam when you begin. Write clearly