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Unformatted text preview: Name:___________________ Last First UNLV, DEPARTMENT OF MECHANICAL ENGINEERING MEG 207, Spring 2009, Third Test Closed Book, one page of handwritten notes allowed. Enter the answer for each question into the space provided. Enter SI units in all answer spaces with brackets ( ). 1. (15 points) Point A of linkage ABC moves downward vertically with constant velocity v A = 2 m/s. AB is coupled to rod BC, which is fixed at C. Determine, for AB at angle Θ = 30 o as shown: (a) the angular velocity of rod AB. (b) the velocity vector of point B of the linkage (i- and j-components) (c) the coordinates of the instantaneous center of the rod AB at the angle Θ = 30 o . Mark the instantaneous center location in the figure at left. All coordinate units are in meters. Use unit vectors i and j. Frame origin is at C. Answer (a) Instantaneous Center of bar AB is at (0, 2.73), see crosshair in drawing. Therefore ω AB = vA/(1m) = 2 rad/s ccw (b) vB = ω AB*1.73 meters = -3.464 m/s *i Version B (α) ω AB = vA/(1m) = 4 rad/s ccw (b) vB = ω AB*1.73 meters = + 6.92 m/s *i Answer ω AB = vA/(1m) = 2 rad/s V B = -3.464 m/s *i B Inst. CTR at : (0i, 2.73j) in meters v A = 2 m/s C B 2 m 1 m 3 o i Unit vectors J Origin at C x A y 2. (20 points) A uniform rectangular cabinet having dimensions shown and mass m = 50 kg is placed onto a cart of mass 10 kg as shown. No slipping between cabinet and cart....
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- Spring '09
- Acceleration, Euclidean vector, Rod AB, unit vectors