THE UNIVERSITY OF BRITISH COLUMBIA 2013/2014 WINTER SESSION SESSIONAL EXAMINATIONS PHYSICS 170 MECHANICS I 8:30 am to 11:00 am, Wednesday, April 23, 2014 MARKS This exam counts for a total of 70 marks towards your Final Grade for the course. The exam consists of 4 questions. Questions 1 and 2 are each worth 20 marks. Questions 3 and 4 are each worth 15 marks. Write all work to be marked in the Answer Booklets provided. NUMERICAL ANSWERS You must give numerical answers correctly to three figures and with correct units to get any marks for your numerical answers. No marks are given for correctly solving incorrect equations. CALCULATOR You may use a graphing calculator. INFORMATION SHEET You may consult one 8 1/2 inch by 11 inch hand-written double-sided Information Sheet. Your Information Sheet must not contain any sample problems or solutions to sample problems. Put your name and student number on your Information Sheet. You must hand in your Information Sheet with your Answer Booklet in order for your exam to be marked.
PHYSICS 170 MECHANICS I Final Exam: 8:30 am to 11:00 am, Wednesday, April 23, 2014 QUESTION 1 (20 marks) The diagram below shows a rigid body AB in equilibrium in the horizontal plane. Cylinder D weighs 30 lb. The weight of AB may be neglected. AB is acted on by a couple moment M = (50i +60] +70k) lb-ft at B. AB is held in equilibrium by a frictionless pin at A and by a cable BC. a) Draw a large, clear free-body diagram for AB. Show also the Cartesian unit vectors and the numerical values of the coordinates of B, C and the point where the load D is attached to AB. (4 marks) b) Determine Cartesian component force equations of equilibrium for AB. (4 marks) c) Determine Cartesian component moment equations of equilibrium for AB. (8 marks) d) Solve the Cartesian component equations of equilibrium for AB to determine the Cartesian components of reaction at A and the magnitude of the force in the cable. (4 marks) Z. 1 ft, 1E 0 A 2 ft 0 B 2 ft 2 ft 6 ft 2 ft y D
PHYSICS 170 MECHANICS I Final Exam: 8:30 am to 11:00 am, Wednesday, April 23, 2014 QUESTION 2 (20 marks) In the diagram below, particle C of mass 1.2 kg travels along the curved guide due to rotation of the smooth forked rod. Motion is in the horizontal plane. The rod exerts a force F on C. The guide exerts a normal force N and a kinetic frictional force Fr on C. The coefficient of kinetic friction between C and the guide is 0.5. The size of C may be neglected. At the instant shown, r=0.8m, + =- 0.3m/s, F =- 0.4m/s2, 0 =60°, 9=0.9 rad/s, Ö=1.1 rad/s2 , dr | de = - 0.333 m/rad . a) Draw a large, clear free-body diagram for C at the instant shown. On this diagram, draw radial (r) and transverse (0)