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Honors Physics: Review Problems for Final Spring 2013 You need not do all these problems. Choose problems in areas that you were unsure of in the past and see if you get the correct answers now. If not, ask in class. Disclaimer: I did not check answers if the solution appeared reasonable. If you find errors, please let me know. 1. A block with a mass of 6.0 kg and an initial velocity of 5.0 m/s collides with a stationary block with a mass of 4.0 kg on a frictionless surface. After the collision, the blocks stay together. What will be the final velocity of the two-block system? Is the collision elastic or inelastic? (3.0 m/s, inelastic; AC) 2. If a ball is thrown up into the air with an initial velocity of 30. meters per second at a 65 degree angle at a starting elevation of 123 meters, how far does the ball travel horizontally before it hits the ground 123 meters below where it was thrown? (120 m; DC) 3. A blue bumper car with a mass of 2.5 X 104 kg travels at a velocity of 6.0 m/s. It collides into a stationary red bumper. Upon colliding with the red bumper car, the blue car rebounds on its own with a velocity of 2.0 m/s. The collision sends the red bumper car forward with a speed of 3.5 m/s. What is the mass of the red bumper car? (57000 kg; PDM) 4. Two blocks are pushed across a frictionless surface with 120. N of force and experience an acceleration of 11m/s and 16m/s respectively. When the two blocks are stopped .025 km apart, what is their gravitational attraction toward each other. (2.2x10-10 N; KA) EC: What is the capital of Croatia? 5. Little Johnny is lost in the woods. When he realizes he is lost, he decides that he must travel 17 km due south to reach camp. Confused, Johnny begins to walk 34 degrees north of east for 2.0 km. Trying to fix his mistake, he walks 10. km at 84 degrees south of west. Now he tries again, walking 3.0 km at 63 degrees south of east. In what direction and for what distance must Johnny walk to return to camp? (5,800 m at 70.0 South of West; MH) 6. A 4.20 g bullet moving at 872 m/s strikes a 500. g wooden block at rest on a frictionless surface. The bullet emerges, traveling in the same direction with its speed reduced to 424 m/s. (a) What is the resulting speed of the block? (b) What is the speed of the bullet-block center of mass? (3.76 m/s, 7.26 m/s; JH) 7. A 6.25 kg box slides at a constant 2.00 m/s down a 42.0 degree slope. Find the coefficient of kinetic friction. (0.900; KO) 8. A 5.00km piece of wire with a cross-sectional area of .7889 mm² has a total resistance of .899Ω. What is the conductivity of the wire? ( 7.13x109(Ω m) -1; SE) 9. There are two objects that are 72.0 centimeters apart. The first object has a charge of +156 nanocoulombs while the other has a charge of +48.0 nanocoulombs. a) What is the electrostatic force between them. b) Is that force attractive or repulsive? c) When both objects are touched together, what is the charge leftover on each object? d) What is the electrostatic force between them after they are touched together and separated by the same distance again? (a) F= 1.30 x 10-4 N b) The force is repulsive because it is a positive number. c) +54.0 nC on each object d) F= 5.06 x 10-5 N; MM) 10. You push a 2.0 kg block against a horizontal spring, compressing the spring by 15 cm. Then you release the block, and the spring sends it sliding across a tabletop. It stops 75 cm from where you released it. The spring constant is 200. N/m. What is the block-table coefficient of kinetic friction? (0.15; KS) 11. Two charged objects are brought .50 meters away from each other. One has a charge of -50. C. If the force between the two is 275N what is the other charge? (1.5 X 10 -10C; OM) 12. A circuit with a 120V emf device has one 3.0 Ո resistor that is connected in series to a 4.0 Ո resistor and a 6.0 Ո resistor that are connected in parallel. a) Find the equivalent resistance for the 4.0Ո and 6.0Ո resistors that are connected in parallel. b)Find the total resistance for the entire circuit. c)Find the total current in the circuit. d)Find the current through the 3.0Ո resistor. e) Find the voltage drop through the 3.0Ո resistor. f) Find the current through the 6.0Ո resistor g)Find the current through the 4.0Ո resistor. (2.4 Ո, 5.4 Ո, 22A, 22A, 67V, 8.9A, 13A; BK) 13. An ambulance moving at 30.0 m/s passes by both a person sitting on a sidewalk and a police car moving at 22.0 m/s. If the ambulance’s siren emits at a frequency of 680. Hz what is the frequency heard by (a) the person sitting and (b) the policeman in the police car? (assume 343.5 m/s for speed of sound) (625 Hz, 665 Hz; RS) 14. A sled filled with children with a total mass of 30. kg slides, from rest, down a 20. m hill at 8.2 m/s. (a) What is the change of gravitational potential energy of the sled-earth system from when the sled was at rest to when the sled was sliding down the hill? (b) What is the kinetic energy of the sled right before it hits the bottom of the hill and stops? (5900 J, 1.0 x 103 J; AL) 15. If a spring with a spring constant of 75. N/m is compressed 7.0 m, how much work is done on the spring? (-1837.5 J; AK) 16. A black car that has a mass of 6.3 x 105 kg is moving at 60. m/s. A red car that has a mass of 4.7 x 105 kg breaks down and is in the middle of the road. The black car crashes into the red car and the rear end of the red car and the front of the black car lock on. What is the velocity of the attached cars? If the cars did not join, what velocity would the red car be moving at after the collision if the black car came to a complete stop? (34 m/s, 80.m/s; AK) 17. A train with a mass of 6.36 x 106 kg is moving at a speed of 75.0 km/h. The brakes, which produce a net backward force of 1.93 x 106 N, are applied for 22.0 seconds. What is the new speed of the train? How far has the train traveled in this time? (14.1m/s, 384.m; A-MM) 18. Three resistors, 16 ohms, 12 ohms, and 6 ohms are connected in parallel. Find the total resistance and the current drawn through a 140 volt battery. (3.2 ohms, 44 A; CH) 19. An angry child throws his toy dinosaur up in the air at a velocity of 40.0 meters per second at a 30.0 degree angle to the horizontal. A. How far does the dinosaur travel from its starting point? B. What is the maximum height of the dinosaur? (70.7m, 20.4m; AT){ Wow – that is some strong child! Perhaps he/she will become an Olympic star.} 20. If the lowest resonant frequency of a certain violin string is 360. Hz, what is the frequency of the (a) second and (b) third harmonic of the string? (720 Hz, 1080 Hz; EW) 21. An airplane moves at 141 km/h toward the northeast (45 degrees). What is its component velocity in the northward direction? (100. Km/h; SM) 22. A box weighing 300 N is pulled across a flat surface at constant speed by a rope that is at an angle of 25 degrees. If the force of the rope is 180 N, what is the Mu of kinetic friction? (0.7; MR) 23. A roller coaster glides over the crest of a frictionless track at 5.0 m/s. The crest of a hill is at 60.0 m above the starting point. The coaster goes over the crest of the hill, reaches the bottom and immediately encounters another hill with its crest at the height of 37.0 m. How fast is the coaster going at the top of the second crest? If the curvature at the top of the second hill's crest is 20.0 m radius will the rider feel "Weightless"? (26 m/s, Y; JP) 24. Danny starts his parked car and accelerates for 7.22 seconds for a distance of 100. meters. a. Determine the acceleration of Danny’s car.b. As Danny is driving down Smithbridge Road, he suddenly spots a flock of geese crossing the street. He slams on the brakes. The car, which was traveling at 22.5 m/s, skids to a stop with a deceleration of 5.28 m/s 2. How long does it take for the car to come to a complete stop? (3.84 m/s2, 4.26s; AM) 25. What is the potential energy of Becca’s laptop, 15.0 kg, sitting on a table 2.50 m high? With what velocity does it hit the ground? (368 J, 7.00 m/s; RC) 26. An airplane has a takeoff speed of 68.3 m/s and it requires 1279 m to reach that speed. Find the acceleration of the plane and the time needed to reach this speed. (1.83 m/s 2, 37.3s; SS) 27. An Imperial Stormtrooper was enjoying the local scenery and conversing with some Ewoks on the planet of Endor, when he heard a speeder. At a speed of 15 m/s, he traveled away from the sound to warn the others back at his base. The Stormtrooper noticed the other bike was emitting a sound at 200. Hz. Traveling away from the Stormtrooper, a member of the Rebel army was actually emitting a sound of 310 Hz from his speeder bike. At what speed was the Rebel traveling? (170 m/s; RS) 28. A transverse wave has a speed of 200 m/s when the string tension is 80 N. What value must the tension be changed to in order to create a wave with the speed of 300 m/s? (270 N; AJ) 29. There are four resistors in a circuit with a battery. In a rectangle formation, side one has the battery, side two has resistor 1, side three has resistors 2 and 3 in parallel, and side four has resistor four. R1= 6.0 ohms, R2= 4.0 ohms, R3= 5.0 ohms, and R4= 8 ohms. Find a) the total resistance. b) What would happen if R1 broke? (16 ohms, current stops; EE) 30. Romana and her dog, Sheila, are on walk to visit her friend’s house. Unfortunately Sheila does not get along with Carl, Romana’s friend’s dog. Before entering the house, Sheila quickly sits down on the porch and refuses to move. Romana pulls on Sheila’s leash with 67.0 N of force at an angle of 30.0º above the horizontal. Determine the horizontal and vertical components of the tension force. (58.0N, 33.5 N; MG) 31. Find the center of mass between 4 linear objects of equal masses positioned at x= (6,18,1,3)? (7m; AR) 32. What is the third lowest frequency that will resonate on a string 5.00 m long if the speed of waves on the string is 145 m/s? (43.5 Hz; JG) 33. A 40.0ohm resistor is connected in parallel to a 10. ohm resistor. The two resistors in parallel are connected in series with a 20. ohm resistor. The circuit is placed across a 40. volt difference of potential. A) What is the equivalent resistance of the entire circuit? B) What is the equivalent resistance of the parallel portion of the circuit. C) What is the current in the entire circuit? D) What is the voltage drop in the 20. ohm resistor? (28 ohm, 8.0 ohm, 1.4A, 29V; JV) 34. Jim walked up a hill and upon reaching the top of the hill, which dropped off sharply on the other side, Jim threw his water bottle out over the ledge. The water bottle traveled 6.8 m/s at 60.0 degrees to the horizontal. Determine how far above the launch height the bottle went and how far the bottle traveled horizontally when it reached its launch height on the descent. (0.78m, 4.5 m; WF) 35. There are two objects of different mass separated by a certain distance. One object of mass 5.0 kg is at position (5,0) and another object of mass 12.0 kg is at position (14,0). A. Find the position of the center of mass of the two objects B. Find the gravitational force of attraction between the two objects ((11,0), 4.9 X 10-11 N; VN) 36. A massive cannon ball is shot at 40m/s at a marble of 1cm in diameter. The two collide in a head on collision. What is the final velocity of the marble? ( 80 m/s; SL) 37. An open pipe produces a second harmonic standing wave of frequency 700. Hz at 23.0 degrees Celsius. Determine the length of the pipe. (0.493 m, ED) 38. Kevin has a mass of 95.0 kg and Alex has a mass of 75.0 kg. They are 5.00 m apart from each other. How much force are Kevin and Alex exerting on one another? (1.90 X 10-8 N; EJ) 39. A mermaid is straight chilling 2 meters high on a rock above the water. It is 72.5 Kg. If it falls, at what velocity would it hit the water? (6 m/s; DM) 40. Mrs. Johnson throws a baseball straight up in the air with a velocity of 25m/s. Find a) the time it takes for Mrs. Johnson to catch the ball, b) the velocity of the ball just before Mrs. Johnson catches it, and c) how high the ball travels. (5.1 s, 25 m/s, 32 m; BG) 41. An 8.0Ω and a 4.0Ω resistor are connected in parallel and the combination is connected to a 6.0Ω resistor in series. The circuit is hooked up to a 12.0V source. What is current through each resistor? (.46A, .92A, 1.4A; BW) 42. A 15v battery is connected to 5 resistors. Two of the resistors are connected in series and the other three resistors are in parallel. The two resistors in series are of 2.0 ohms and 3.0 ohms. The three in parallel are all 3.0 ohms. a)What is the total resistance throughout the circuit? b)What is the total current in the circuit? b)How much current is going through each resistor? (6.0 ohms, 2.5A, c) 2.5A, 2.5A, .83A, .83A, .83A; DH) 43. A 50. kg block on a horizontal table is pulled at a constant speed by a force of 70. N exerted on a rope making an angle of 30.0° below the horizontal. What is the coefficient of sliding friction for the block on the tabletop surface? (0.12; MP) 44. A 5.0 C and a 1.0 C sphere are 10.m apart. What is the electrostatic force between the two spheres. (4.0 X 108 N; JL) 45. A projectile is projected with a speed of 30 m/s at an angle of 600 to the horizontal. Calculate the a) maximum height it will reach, and b) the time of flight. (34.5m, 5.3s; KH) 46. What is the potential energy of a 20,000g object suspended 170m in the air? (33000 J; JCZ) 47. At exactly 2pm a BB is launched at an angle of 45 degrees with an initial velocity of 6,700m/s. How far does it travel? What is the maximum height? When does it hit the ground? ( 2300000m, 1400000m, 2:08:3.43 PM ignoring s.f.; JCZ) 48. 1. 2. 3. Using the above circuit diagram What is the total resistance of the circuit? What is the current through the Ammeter? What is the voltage drop across each resistor? ( 17 Ω, 3.5 A, 42 V for 12 Ω , 18V for 15 Ω, 11.5V across 5Ω, 6.5V across the 4.0Ω and the 8.0Ω; AS)