THE UNIVERSITY OF BRITISH COLUMBIA 2012/2013 WINTER SESSION SESSIONAL EXAMINATIONS PHYSICS 170 MECHANICS I 7:30 pm to 8:30 pm, Wednesday, February 6, 2013 MARKS This exam counts for a total of 20 marks towards your Final Grade for the course. The exam consists of 2 questions each worth 20 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 Midterm Exam: 7:30 pm to 8:30 pm, Wednesday, February 6, 2013 QUESTION 1 (20 marks) The diagram below shows a rigid body ABCD acted on by three forces and a couple moment. a) Draw a large, clear diagram for ABCD showing the forces and the couple moment. b) Replace the force and couple moment system by an equivalent resultant force FR and couple moment (MR)A acting at A. Express FR as a Cartesian vector. (4 marks) (3 marks) Express (MR)A as a Cartesian vector. (8 marks) c) The force-couple system at A can be replaced by a single equivalent force by moving FR to a point Q on the horizontal member CD. The position vector for Q is To = (xi +5])m. Determine the value of x. (5 marks) y 4 300 N 1 1 m - 2 m C B 3 m D 250 N 5 3 4 2 m 400 NĀ·m 60Ā° 3 m 500 N * x A
PHYSICS 170 MECHANICS I Midterm Exam: 7:30 pm to 8:30 pm, Wednesday, February 6, 2013 QUESTION 2 (20 marks) The diagram below shows a rigid body AB in equilibrium in the horizontal plane. AB is acted upon by forces F = - 800 k N and F2 = 350 ] N as shown. The weight of AB may be neglected. AB is held in equilibrium by a smooth journal bearing at A and by cables BC and BD. a) Draw a large, clear free-body diagram for AB. (4 marks) b) Determine the Cartesian component force equations of equilibrium for AB. (4 marks) c) Determine the vector moment equation of equilibrium for AB. (4 marks) It is convenient to take moments about B. d) Determine the Cartesian component moment equations of equilibrium for AB. (4 marks) e) Solve the Cartesian component equations of equilibrium to determine the Cartesian components of reaction at A and the magnitudes of the forces in the cables. (4 marks) Z C 3 m A 2 m 3 m D 6 m 4