P140_E3_W04

# P140_E3_W04 - Physics 140 Winter 2004 Midterm 3 1. (P) The...

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Physics 140 Winter 2004 Midterm 3 1 1. (P) The figure below shows an 18.0kg crate of salami sliding down a ramp on a (massless) rope that is wrapped around a disk of radius 0.25m and mass 6.0kg. The coefficient of kinetic friction between the crate and ramp is μ k =0.24. What is the magnitude of the disk’s angular acceleration? a) 3.1 rad/s 2 b) 6.7 rad/s 2 c) 9.8 rad/s 2 d) 11.4 rad/s 2 e) 13.7 rad/s 2 2. (P) A uniform solid sphere rests suspended from a cord anchored at point P along an inclined plane. Which of the following statement(s) is(are) true ? a) The torque about point P due to the weight of the sphere is zero. b) The torque about point P due to the tension in the cord is zero. c) The torque about point C due to the normal force of the incline on the sphere is zero. d) both b) and c) e) all of a), b) and c) C P

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Physics 140 Winter 2004 Midterm 3 2 3. (P) A rigid assembly consists of a thin hoop of radius R and mass m attached to a thin rod also of mass m and length 2 R rests in the vertical position shown in the figure below. Given a tiny nudge (involving negligible energy) from behind, the assembly rotates about the horizontal axis shown. What is its angular speed as it passes through the inverted (upside-down) orientation? a) (96g/65 R ) 1/2 b) (33g/15 R ) 1/2 c) (48g/17 R ) 1/2 d) (17g/12 R ) 1/2 e) (8mg/15 R ) 1/2 4. Kepler’s second law of planetary motion – the observation that the orbits of planets sweep out equal areas around the Sun in equal times – mainly reflects the conservation of which physical quantity? a) mechanical energy. b) angular momentum. c) linear momentum. d) gravitational potential energy. e) mass. rotation axis hoop rod
Physics 140 Winter 2004 Midterm 3 3 5. Three coplanar bodies A, B and C with masses m , 2 m , and 8 m , respectively, are shown below. At what ( x,y ) location should a fourth body D of mass 8 m be placed such that the total gravitational force on body A is zero? a) ( –2 1/4 d , 2 1/4 d ) b) (2 1/4 d , d /2 1/4 ) c) (2 1/4 d , –2 1/4 d ) d) ( d /2 1/4 , – d /2 1/4 ) e) ( d /2 1/4 , –2 1/4 d ) 6. A 2kg box of pepper-encrusted salamis sits 0.5m from the right edge of a uniform 4kg beam of length 2m. The markings on the beam are at quarter-length intervals. Both the beam and the salamis rest atop a pair of rollers A and B, located at the center and

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## This note was uploaded on 04/02/2008 for the course PHYSICS 140 taught by Professor Evrard during the Winter '07 term at University of Michigan.

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P140_E3_W04 - Physics 140 Winter 2004 Midterm 3 1. (P) The...

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