Phys 111 Exam October 17, 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
1. You throw a baseball straight up. Compare the sign of the work done by gravity while the ball goes up with the sign of the work done by gravity while it goes down. A) The work is positive on the way up and positive on the way down. B) The work is positive on the way up and negative on the way down. C) The work is negative on the way up and positive on the way down. D) The work is negative on the way up and on the way down because gravity is always downward.. Two objects, one of mass m and the other of mass m, are dropped from the top of a building. If there is no air resistance, when they hit the ground A) both will have the same kinetic energy. B) the heavier one will have twice the kinetic energy of the lighter one. C) the heavier one will have four times the kinetic energy of the lighter one. D) the heavier one will have half the kinetic energy of the lighter one. E) the heavier one will have one-fourth the kinetic energy of the lighter one. 3. A 3.1 kg box is pulled upward 6.0 m along the surface of a ramp that rises at 37 above the horizontal. How much work does gravity do on the box during this process? A) -1100 J B) -110 J C) -140 J D) -180 J E) 10 J 4. The kinetic friction force that a horizontal surface exerts on a 60.0-kg object is 50.0 N. If the initial speed of the object is 5.0 m/s, what distance will it slide before coming to a stop? A) 15.0 m B) 30.0 m C) 10 m D) 750 m E) 375 m
5. A 111-kg seal at an amusement park slides from rest down a ramp into the pool. The top of the ramp is 1.75 m higher than the surface of the water and the ramp is inclined at an angle of 6.5 degree above the horizontal. If the seal reaches the water with a speed of 4.5 m/s, what is the work done by kinetic friction? A) 903 J B) 501 J C) 0 D) - 501 J E) -903 J 6. A block slides down a frictionless inclined ramp and experiences no significant air resistance. If the ramp angle is 17.0 above the horizontal and the length of the surface of the ramp is find the speed of the block as it reaches the bottom of the ramp, assuming it started sliding from rest at the top. A) 10.7 m/s B) 114 m/s C) 7.57 m/s D) 19.6 m/s E) 1.4 m/s 7. A bead is moving with a speed of 0 m/s at position A on the track shown in the figure. This track is friction-free, and there is no appreciable air resistance. What is the speed of the bead at point C? A) 0 m/s B) 34 m/s C) 69 m/s D) 0 m/s E) 8 m/s 3
8. An object is under the influence of a force as represented by the force vs. position graph in the figure above. What is the work done as the object moves from 0 m to 1 m? A) 0 J B) 30 J C) 0 J D) 40 J E) 70 J 9. A 0.140-kg baseball is dropped and reaches a speed of 1.0 m/s just before it hits the ground and bounces. It rebounds with an upward velocity of 1.00 m/s. What is the change of the ball's momentum during the bounce? A) 0.080 kg m/s upwards B) 0.080 kg m/s downwards C) 0.308 kg m/s upwards D) 0.308 kg m/s downwards E) 0.000 kg m/s 10. A 0.140 kg baseball is thrown horizontally with a velocity of 8.9 m/s. It is struck with a constant horizontal force that lasts for 1.85 10-3 s, which results in a velocity of 37.0 m/s in the opposite direction. What was the magnitude of the horizontal force? A) 0.613 10 3 N B).19 10 3 N C).80 10 3 N D) 4.99 10 3 N E) 10.0 10 3 N 4
11. A 100-kg car moving at suddenly collides with a stationary car of mass If the two vehicles lock together, what is their combined velocity immediately after the collision? A) 6.9 m/s B) 8.6 m/s C) 1.1 m/s D) 5.5 m/s E) 19.0 m/s 1. Three small masses are positioned as follows:.0 kg at (0.0 m, 0.0 m),.0 kg at (.0 m, 0.0 m), and 4.0 kg at (.0 m, 1.0 m). Determine the coordinates of the center of mass (or center of gravity) of this system. A) (0.50 m, 1.5 m) B) (1.5 m, 0.50 m) C) (.5 m, 1.5 m) D) (.5 m, 0.50 m) E) (0.5 m, 1 m) 13. A race car traveling at a constant speed of 50 m/s drives around a circular track that is 500 m in diameter. What is the magnitude of the acceleration of the car? A) 0 m/s B) 1.0 m/s C) 10 m/s D) 0.63 m/s E). m/s 14. A figure skater is spinning slowly with arms outstretched. She brings her arms in close to her body and her moment of inertia decreases by 1/3. By what factor does her angular momentum change? A) 9 B) 3 C) 1/3 D) 1/9 E) It doesn't change. 5
15. A child is trying to stack two uniform bricks, each 4 cm long, so they will protrude as far as possible over the edge of a table without tipping over, as shown in the figure. What is the maximum possible overhang distance d? A) 10 cm B) 1 cm C) 14 cm D) 16 cm E) 18 cm 16. A store's sign has a mass of 0.0 kg and is 3.00 m long. It is uniform, so its center of gravity is at the center of the sign. It is supported horizontally by a small loose bolt attached to the wall at one end and by a wire at the other end, as shown in the figure blow. What is the magnitude of the net force that the bolt exerts on the sign? A) 464 N B) 3 N C) 00 N D) 10 N E) 300 N 17. A 95-N force exerted at the end of a 0.3-m long torque wrench produces a torque of 15 N m. What is the angle (less than 90 ) between the wrench handle and the direction of the applied force? A) 30 B) 4 C) 36 D) 4 E) 1 6
18. A Ferris wheel rotating at 0 rad/s slows down with a constant angular acceleration of magnitude 5.0 rad/s. How many revolutions does it make while slowing down before coming to rest? A) 40 B) 0 C) 1 D) 6.4 E) 3. 19. A wheel having a moment of inertia of 5.00 kg m starts from rest and accelerates under a constant torque of 3.00 N m for 8.00 s. What is the wheel's rotational kinetic energy at the end of 8.00 s? A) 57.6 J B) 64.0 J C) 78.8 J D) 1 J E) 1 J 0. What is the distance from the center of the Moon to the point between Earth and the Moon where the gravitational pulls of Earth and Moon are equal? The mass of Earth is 5.97 104 kg, the mass of the Moon is 7.35 10 kg, the center-to-center distance between Earth and the Moon is 3.84 108 m, and G = 6.67 10-11 N m/kg. (If need, ) A) 3.45 108 m B) 3.84 107 m C) 4.69 106 m D) 3.83 106 m E) 4.69 107 m 7
Record Sheet of Exam #, Physics 111, Fall 017 You may fill in this sheet with your choices and take it with you for comparison to the posted answers. 1 11 1 3 13 4 14 5 15 6 16 7 17 8 18 9 19 10 0 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 11 6.67 10 / / 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 1 1 1 L E KE PE mv kx ka T m g
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 0 0 1 1 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 1.01 10 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 1 1 1 Temperature and Heat: 5 TC TF 3 TK TC 73.15; L L0T ; V V0T ; Q mct 9 4 8 4 Q ml ; Q ml ; Q / t kat / L; Q / t eat ; 5.67 10 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 1.3810 J / K B A B 3 1 3 3 3 NA 6.010 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