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Unformatted text preview: truong (ajt2287) HW#3 - Forces I hester (WVPHYSICSC2011) 1 This print-out should have 33 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 (part 1 of 2) 10.0 points A book is at rest on an incline as shown below. A hand, in contact with the top of the book, produces a constant force F hand vertically downward. F hand B o o k The following figures show several attempts at drawing free-body diagrams for the book. Which figure has the correct directions for each force? The magnitudes of the forces are not necessarily drawn to scale. 1. weight force friction normal 2. weight force normal friction 3. weight friction force normal 4. weight force normal friction 5. weight normal friction force 6. normal force friction weight 7. weight friction normal force 8. normal friction weight force 002 (part 2 of 2) 10.0 points For the normal force exerted on the book by the wedge in the diagram, which force(s) complete(s) the force pair for Newtons third law (action-reaction)? 1. the component of F hand pointing perpen- dicular to the surface of the incline 2. the component of gravity pointing parallel to the surface of the incline truong (ajt2287) HW#3 - Forces I hester (WVPHYSICSC2011) 2 3. the pull of the book on the earth 4. the normal force exerted on the wedge by the book 5. the sum of the component of gravity per- pendicular to the surface of the incline and the component of F hand perpendicular to the surface of the incline 6. the pull of the earth on the book 7. the component of gravity pointing per- pendicular to the surface of the incline 003 10.0 points A toy car is given a quick push so that it moves up an inclined ramp. After it is released, it moves up, reaches its highest point and moves back down again. Friction is so small it can be ignored. What net force acts on the car? 1. Net constant force up the ramp 2. Net increasing force down the ramp 3. Net force of zero 4. Net constant force down the ramp 5. Net decreasing force up the ramp 6. Net decreasing force down the ramp 7. Net increasing force up the ramp 004 10.0 points An elevator starts from rest with a constant upward acceleration and moves 1 m in the first 1 . 5 s. A passenger in the elevator is holding a 7 . 7 kg bundle at the end of a vertical cord. What is the tension in the cord as the ele- vator accelerates? The acceleration of gravity is 9 . 8 m / s 2 . Answer in units of N 005 10.0 points A spider of mass m is sitting in a perfectly symmetric web (in a vertical plane with 45 angles between the web lines) as shown in the figure below, where T i s denote the tensions along the lines which are connected to the spi- der at the center with i = 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ....
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- Spring '11