PHYSICS 170 MECHANICS 1: March Exam: 6:00 PM, Thursday, March 9, 2023 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 15 marks, for a total of 30 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 9, 2023 QUESTION 1 (15 marks) The diagram below shows a rigid forked rod ACB that is supported in equilibrium by a smooth collar (see diagram) at A, a thrust bearing at B and a cable CD. An applied force F acts at C as shown. The supports at A and B are in proper alignment and exert only force reactions on the rod. The weight of the rod may be neglected. Note that the shaft that passes through the two bearings is not part of the rod ACB. a) Draw a large, clear free-body diagram for ACB. (4 marks) (4 marks) b) Determine Cartesian component force equations of equilibrium for ACB. c) Determine a vector moment equation of equilibrium in determinant form for ACB. Take moments about C. (2 marks) d) Determine Cartesian component moment equations of equilibrium for ACB. (3 marks) e) Determine numerical values for the Cartesian components of reaction at A and B, and the tension in the cable. Note that it is not too difficult to solve a correct set of equilibrium equations by hand. (2 marks) Z D 2 m 0.5 m B 0.5 m A x 1 m 1 m C y F = {50 i + 40 j - 80 k} N
PHYSICS 170 MECHANICS 1: March Exam: 6:00 PM, Thursday, March 9, 2023 QUESTION 2 (15 Marks) In the diagram below the 50-lb board AB is placed across the channel and a 100-lb girl attempts to walk across it. The coefficient of static friction at A and B is Us =0.4. The weight of the board acts at its geometric center. Ignore any friction