WebAssign Ch. 8 Regular Physics (Homework) Current Score : 23.85 / 40 ue : Monday, October 3 2011 11:00 PM MT THOMAS FOWLR Physics, section T1_P5_Carlson, Instructor: Sarah Carlson 1. /1.9 points GPhys09 8.AC.063. What does a spin cycle of a washing machine do? xplain in terms of the forces on the clothes and water. 2. 1.9/1.9 points Previous Answers GPhys09 8.MC.048. A bicycle wheel rotates at a constant 30 rev/min. Is its angular velocity decreasing, increasing, or constant? decreasing increasing constant 3. 1.9/1.9 points Previous Answers GPhys09 8.MC.050. o all parts of arth rotate at the same rate? xplain because they all rotate the same amount of degrees during a givin time 4. 1.9/1.9 points Previous Answers GPhys09 8.MC.054. Rank the torques on the five doors shown below from least to greatest. te that the magnitude of all the forces is the same.
A A A A A C < C < C < C < C 5. 1.9/1.9 points Previous Answers GPhys09 8.MP.082. What is the torque on a bolt produced by a F = 13 force exerted perpendicular to a wrench that is l = 22 cm long, as shown below? 2.86 m 6. 1.9/1.9 points Previous Answers GPhys09 8.MP.086. A 29.5 kg board, 4.00 m long, is being help up on one end by Ahmed. He calls for help, and Judi responds.
(a) What is the least force that Judi could exert to lift the board to the horizontal position? 144.69 What part of the board should she lift to exert this force? At the opposite end of Ahmed (b) What is the greatest force that Judi could exert to lift the board to the horizontal position? 289.38 What part of the board should she lift to exert this force? At the middle of the board 7. /1.9 points GPhys09 8.MR.090. Ten bags of top soil, each weighing 185, are placed on a 2.50 m long sheet of wood. They are stacked 0.50 m from one end of the sheet of wood, as shown below. Two people lift the sheet of wood, one at each end. Ignore the weight of the wood, how much force must each person exert? F Left person = F Right person = 8. 0.95/1.9 points Previous Answers GPhys09 8.TC.105. Gerald and velyn carry the following objects up a flight of stairs: a large mirror, a dresser, and a television. velyn is at the front end, and Gerald is at the bottom end. Assume that both velyn and Gerald exert only upward forces. (a) raw a free body diagram showing Gerald and velyn exerting the same force on the mirror. (o this on paper. Your instructor may ask you to turn in this work.)
(b) raw a free body diagram showing Gerald exerting more force on the bottom of the dresser.(o this on paper. Your instructor may ask you to turn in this work.) (c) Where would the center of mass of the television have to be so that Gerald carries all the weigh? to the left of him to the right of him directly above him 9. 1.9/1.9 points Previous Answers GPhys09 7.AC.040. ecide whether each of the orbits shown below is a possible orbit for a planet. (The diagram shows a view from directly above.) (a) (b) (c)
(d) 10. 1.9/1.9 points Previous Answers GPhys09 7.AC.042. What would happen to the value of G if arth were twice as massive, but remained the same size? G would be quadrupled nothing G would be doubled G would be halved 11. 1.9/1.9 points Previous Answers GPhys09 7.MC.028. What happens to the gravitational force between two masses when the distance between the masses is doubled? The force is doubled. The force is unchanged. The force is quartered. The force is halved. 12. /1.9 points GPhys09 8.MP.078. A washing machine's two spin cycles are 355 rev/min and 500 rev/min. The diameter of the drum is 0.43 m. (a) What is the ratio of the centripetal accelerations for the fast and slow spin cycles? a fast /a slow = (b) What is the ratio of the linear velocity of an object at the surface of the drum for the fast and slow spin cycles? v fast /v slow =
13. 1.9/1.9 points Previous Answers GPhys09 7.MC.032. What provides the force that causes the centripetal acceleration of a satellite in orbit? mass gravity magnetism velocity 14. /1.9 points GPhys09 7.MP.053. The figure below shows a Cavendish apparatus like the one used to find G. It has a large lead sphere that is m 1 = 5.9 kg in mass and a small sphere with a mass of m 2 = 0.044 kg. Their centers are separated by 0.055 m. Find the force of attraction between them. (Use G = 6.67 10 11 m 2 /kg 2.) 15. /1.9 points GPhys09 7.MP.055. Tom has a mass of 69.0 kg and Sally has a mass of 55.0 kg. Tom and Sally are standing 20.0 m apart on the dance floor. Sally looks up and sees Tom. She feels an attraction. If the attraction is gravitational, find its size. Assume that both Tom and Sally can be replaced by spherical masses. (Use G = 6.67 10 11 m 2 /kg 2.) 16. /1.9 points GPhys09 7.MP.057. Two bowling balls each have a mass of 6.4 kg. They are located next to each other with their centers 20.6 cm apart. What gravitational force do they exert on each other? (Use G = 6.67 10 11 m 2 /kg 2.)
17. /1.9 points GPhys09 6.AC.041. A batter hits a pop up straight up over home plate at an initial velocity of 16 m/s. The ball is caught by the catcher at the same height that it was hit. At what velocity does the ball land in the catcher's mitt? eglect air resistance. (Take the positive direction to be upwards.) m/s 18. /1.9 points GPhys09 6.AC.045. A quarterback throws a football at 25 m/s at a certain angle above the horizontal. If it took the ball 3.4 s to reach the top of its path, how long was it in the air? s 19. 1.9/1.9 points Previous Answers GPhys09 6.AC.047. Imagine that you are sitting in a car tossing a ball straight up into the air. (a) If the car is moving at constant velocity, will the ball land in front of, behind, or in your hand? The ball will land in front of your hand. The ball will land in your hand. The ball will land behind your hand. (b) If the car rounds a curve at constant speed, where will the ball land? The ball will land beside you, toward the inside of the curve. The ball will land in your hand. The ball will land beside you, toward the outside of the curve. The ball will land behind your hand. 20. 1.9/1.9 points Previous Answers GPhys09 6.CR.092. Plot the data in the table below on a position time graph. (o this on paper. Your instructor may ask you to turn in this graph.)
Find the average velocity in the time interval between 0.0 s and 3.0 s. 5 m/s 21. 2/2 points Previous Answers GPhys09 6.MC.036. (a) Can you go around a curve with zero acceleration? xplain. acceleration is a change in direction or speed (b) Can you go around a curve with constant acceleration? xplain. you are changing your direction during the curve