UNIVERSITY OF BRITISH COLUMBIA 2018/2019 WINTER SESSION MARCH EXAMINATION PHYSICS 170 MECHANICS I 8:00 pm to 9:00 pm, Tuesday, March 5, 2019 MARKS This exam counts for a total of 30 marks towards your Final Grade for the course. The exam consists of 2 questions. Each question is worth 15 marks. Write all work to be marked in the Answer Booklet provided. NUMERICAL ANSWERS Write numerical answers to three significant figures with units. 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 March Exam: 8:00 pm to 9:00 pm, Tuesday, March 5, 2019 QUESTION 1 (15 marks) The diagram below shows a rigid body held in equilibrium by journal bearings at A, B and C. The body is acted upon by a force F as shown and by a couple moment M = (2007 - 300] + 400k) N . m . The magnitude of F is 100 N. The journal bearings are smooth and only exert force reactions on the body. The weight of the body may be neglected. a) Draw a large, clear free-body diagram for the body. (3 marks) b) Determine Cartesian component force equations of equilibrium for the body. (4 marks (5 marks) c) Determine Cartesian component moment equations of equilibrium for the body. d) The vertical component of reaction at A is 200 N. Determine the numerical values of the components of reaction at C. (3 marks) z C A 2 m 2 m B X 30° 1 m 0.75 m 60° y F
PHYSICS 170 MECHANICS I March Exam: 8:00 pm to 9:00 pm, Tuesday, March 5, 2019 QUESTION 2 (15 marks) The diagram below shows two wedges A and B. A rests on a frictionless horizontal surface. B rests against a frictionless vertical surface. B rests on A. The sloped surface between A and B makes an angle of 15 degrees with the horizontal. A horizontal 100 N force acts to the right on A. A vertical 200 N force acts downwards on B. A friction force acts on the sloped surface between A and B. The weight of the wedges may be neglected. The system is in equilibrium. a) Draw large, clear free-body diagrams for the wedges. (4 marks) b) Determine equations of equilibrium for the wedges. (5 marks) c) Determine numerical values for the force that the horizontal surface exerts on A, the force that the vertical surface exerts on B, and the friction and normal forces acting between A and B. (4 marks) d) Determine the numerical value of the coefficient of static friction between A and B if A and B are impending to slide. (2 marks) 200