MECE 102: Engineering Mechanics Lab A First Year Course in Newtonian Mechanics, Experimentation, and Computer Tools Created by the Faculty of the Mechanical Engineering Department in the Kate Gleason College of Engineering at RIT Week 3 Lecture Newton’s 1st and 2nd Laws • We will study the constrained linear motion of a single body of mass m this week. • We will be using the Ultrasonic Transducer again. • The concept of Vectors will be introduced and utilized when analyzing the experimental data sets. • The concept of FRICTION is introduced. CLICKER: Which of the following statements is FALSE? • Select your Answer: A. B. C. D. E. Velocity is the time rate of change of position. Acceleration is the time rate of change of velocity. Velocity is the time rate of change of acceleration. Snap is the time rate of change of Jerk. The RIT Mascot is a Bengal Tiger. CLICKER: Which of the following statements is FALSE? • Select your Answer: A. B. C. D. E. Velocity is the time rate of change of position. Acceleration is the time rate of change of velocity. Velocity is the time rate of change of acceleration. Snap is the time rate of change of Jerk. The RIT Mascot is a Bengal Tiger. FACET Problem Solving Method Recall from Recitation and Ch. 1.4.2 the problem solving method we will be using in class: • Formulate • Assume • Chart • Execute • Test • Iterate FORMULATE: State the Known Information FORMULATE: State the Known Information FORMULATE: Identify Assumptions CHART: Schematic Diagram CHART: Schematic Diagram Figure 3.2: Schematic Diagram of an Experiment to Measure an Object Sliding Down an Inclined Plane toward Earth. CHART: Schematic Diagram CLICKER: Amontons’ First Law States which of the following? • Select your Answer: A. f = N B. f N C. f N D. f µN E. f µN CLICKER: Amontons’ First Law States which of the following? • Select your Answer: A. f = N B. f N C. f N D. f µN E. f µN Amontons’ 2nd Law States that …… CLICKER: Amontons’ First Law States which of the following? • Select your Answer: A. f = N B. f N C. f N D. f µN E. f µN Amontons’ 2nd Law States that “the force of friction is independent of the apparent contact area.” EXECUTE: Recall Governing Equations CLICKER: Which of the following values is related to the friction force associated with incipient (impending) motion of an object? • Select your Answer: A. Mean horizontal acceleration B. Mean vertical acceleration C. Dynamic coefficient of friction D. Static coefficient of friction CLICKER: Which of the following values is related to the friction force associated with incipient (impending) motion of an object? • Select your Answer: A. Mean horizontal acceleration B. Mean vertical acceleration C. Dynamic coefficient of friction D. Static coefficient of friction CLICKER: For a given interface between two surfaces, the Dynamic coefficient of friction is always greater than the Static coefficient of friction. • Select your Answer: A. True B. False CLICKER: For a given interface between two surfaces, the Dynamic coefficient of friction is always greater than the Static coefficient of friction. • Select your Answer: A. True B. False Thought Experiment • Consider a block of mass, m, resting on a horizontal surface. • Plot the relationship between an applied horizontal force, Fapplied, and the resulting friction force, Ffriction. Vectors Vector representation using 2D Cartesian Coordinates 𝑖 Vector representation using 2D Cartesian Coordinates Vectors Obey the Commutative Law ….. Vectors Obey the Commutative Law ….. And the Associative Law ….. CLICKER: Which of the following coordinate systems may be used when describing a Vector? • Select your Answer: A. Cartesian (x, y, z) B. Polar (r, ) C. Normal , Tangential D. All of the above CLICKER: Which of the following coordinate systems may be used when describing a Vector? • Select your Answer: A. Cartesian (x, y, z) B. Polar (r, ) C. Normal , Tangential D. All of the above CHART: Vector Diagrams 𝒏 𝒕 EXECUTE: The Case of Incipient Motion, s EXECUTE: The Case of Motion, d Week 3 Constrained Linear Motion Experimental Apparatus Week 3 Constrained Linear Motion Experimental Apparatus STUDIO: Central Difference Estimate for Velocity Homework • Prior to LAB tomorrow • Read section 3.2 of the textbook • Watch Week 3 LAB Videos • Complete the on-line LAB quiz in myCourses • Attempt to solve all assigned chapter problems in your logbook before RECITATION. • WEEK 3 HW Problem Set from Section 3.5: 3 8 parts b, d 9 10 parts a, c 14 16 parts b, c 18 20 • Lab Report #2 is due Monday by 6:00pm! The Scribe must upload the LAB REPORT to the myCourses Lab Report #2 Dropbox by 6:00pm Monday! Questions?