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Unformatted text preview: sanchez (ds28677) – homework 13 – Turner – (58220) 1 This printout should have 12 questions. Multiplechoice questions may continue on the next column or page – find all choices before answering. 001 10.0 points A car with mass 752 kg passes over a bump in a road that follows the arc of a circle of radius 48 . 6 m as shown in the figure. The acceleration of gravity is 9 . 8 m / s 2 . 4 8 . 6 m v 752 kg What is the maximum speed the car can have as it passes the highest point of the bump before losing contact with the road? Correct answer: 21 . 8 m / s. Explanation: At the highest point, we have mg N = mv 2 r , where N is the normal force. To get the maximum speed, we need N = 0 . Therefore, v max = √ g r = radicalBig (9 . 8 m / s 2 ) (48 . 6 m) = 21 . 8 m / s . 002 (part 1 of 2) 10.0 points A small sphere of mass m is connected to the end of a cord of length r and rotates in a vertical circle about a fixed point O. The tension force exerted by the cord on the sphere is denoted by T . r O θ What is the correct equation for the forces in the radial direction when the cord makes an angle θ with the vertical? 1. T mg cos θ = + mv 2 r correct 2. None of these 3. T mg sin θ = + mv 2 r tan θ 4. T + mg sin θ = + mv 2 r 5. T + mg cos θ = + mv 2 r 6. T mg sin θ = mv 2 r 7. T mg sin θ = + mv 2 r 8. T mg sin θ = mv 2 r tan θ 9. T mg sin θ = + mv 2 r cos θ Explanation: O θ θ mg T The centripetal force is F c = mv 2 r . This centripetal force is provided by the ten sion force and the radial component of the weight. In this case, they are in opposite sanchez (ds28677) – homework 13 – Turner – (58220) 2 direction, so F c = mv 2 r = T mg cos θ . 003 (part 2 of 2) 10.0 points What is the magnitude of the total accel eration? You may want to first find both the radial and the tangential component of the acceleration. 1. None of these 2.  vectora  = radicalBigg parenleftbigg T m parenrightbigg 2 cos 2 θ + g 2 sin 2 θ 3.  vectora  = radicalBigg parenleftbigg T m parenrightbigg 2 + g 2 4.  vectora  = radicalBigg parenleftbigg T m parenrightbigg 2 + g 2 cos 2 θ 5.  vectora  = radicalBigg parenleftbigg T m parenrightbigg 2 + g 2 sin 2 θ 6.  vectora  = radicalBigg parenleftbigg T m...
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 Spring '08
 Turner
 Physics, Acceleration, Force, Mass, Work, Cos, Correct Answer, Sanchez

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