PHYSICS 170 MECHANICS 1: March Exam: 6:00 PM, Thursday, March 10, 2022 INSTRUCTIONS Answer both questions in the answer booklets that are provided. Please ensure that your name, student number and TUTORIAL SECTION are written clearly on the front page of each booklet you use. Read each question completely and carefully before starting to answer it. You have one hour to complete the exam. You may write with pen and/or pencil. MARKS This exam counts for a total of 30 marks towards your Final Grade for the course. The exam consists of 2 questions, each worth 20 marks, for a total of 40 marks. You should allocate roughly 30 minutes for each question. NUMERICAL ANSWERS You must write numerical answers correctly to three significant figures, with correct units and using engineering notation with an appropriate SI prefix (as necessary) to get full marks for your numerical answers. No marks are awarded for correctly solving incorrect equations. INFORMATION SHEET You may consult one 8 1/2 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, and sign it. You must hand in your Information Sheet with your answer booklet in order for your exam to be marked.
PHYSICS 170 MECHANICS 1: March Exam: 6:00 PM, Thursday, March 10, 2022 QUESTION 1 (20 marks) The diagram below shows a smooth, uniform, rigid rod AB that is supported by a ball and socket joint at A, the wall at B and cable BC. The rod has a mass of 20 kg and its weight acts at the rod's center. There is no friction between the rod and the wall. a) Draw a large, clear free-body diagram for AB. (5 marks) b) Determine Cartesian component force equations of equilibrium for AB. (5 marks) c) Determine a vector moment equation of equilibrium/in determinant form for AB. Take moments about A. (4 marks) d) Determine Cartesian component moment equations of equilibrium for AB. (3 marks) e) Determine numerical values for the Cartesian components of reaction at A, the normal reaction at B, and the tension in the cable. (3 marks) Important: You may find that you have fewer unknowns than equations. Nonetheless, there should still be a unique solution to your equations that you should find using substitution. Do not attempt to find a solution of the full set of equations using your calculator since that will almost certainly result in an error condition. Z C 0.5 m B 2 m A 1 m x 1.5 m y
a) 1 Z 4 (0,0,25) B (0,1 , 2) 6 AZ W6 - x AX (LC,0,0) AYA y e) unknowns: >, MB, Ac, AZ, AY 1 Ax + NR=0 2 Ay -x = 0 3 Az to.sx - 196.2 = 0 4 2.5x6-9-81 = 0 5 2N3 +0-15x - 149-15 = 0 6 - NB +0 - 15x = 0 4 2-5x = 981 XL = 39,24