Download Comprehensive Guide to Lever Mechanics and Test Preparation and more Exams Mechanics in PDF only on Docsity! FCTC Written Study Guide CORRECT QUESTIONS & ANSWERS(RATED A) Classes of Levers - ANSWER Class 1, Class 2, Class 3 Class 1 Levers - ANSWER Fulcrum is in the middle, with the effort (input) force on one side of the fulcrum and resistance (output) on the other side. Mechanical Advantage greater or less than 1 Ex: Seesaw, Crowbar, Pair of Scissors. Class 2 Levers - ANSWER Resistance is in the middle, the effort is applied on one side of the resistance and the fulcrum on the other side. Mechanical Advantage always greater than 1 Ex: Wheelbarrow, nutcracker, bottle opener, or the brake pedal of a car. Class 3 Levers - ANSWER Effort in the middle, the resistance is on one side of the effort and the fulcrum is located on the other side. Mechanical Advantage always less than 1 Ex: Pair of tweezers, human mandible Lever Definitions - ANSWER Lever machine consisting of a beam or rigid rod pivoted at a fixed hinged, or fulcrum. Input Force = Effort Output Force = Load or Resistance What does "fre, 123" mean? - ANSWER Fulcrum is in the middle for Class 1 Levers Resistance (output) in middle for Class 2 Effort (input) in the middle for Class 3 Formula for Determining the head pressure difference between an intake and output - ANSWER 1 vertical foot = 0.433 psi 1 psi = 2.31 vertical feet Overall Test Overview: - ANSWER 1) 30 minute period to read 2 essays - 2 hour time limit begins to answer (100 questions). 2) Watch 2 short videos and answer (20 questions) based on the scenarios. 3) Apply mechanical reasoning (25 questions, i.e. Fluid Dynamics, levers, belt and pulleys, gears) 4) Mathematical Problems (20 questions, i.e. addition, division, angles, area, volume, decimals, ratios, percentages) 5) Recall and Comprehend Technical Information (35 questions, recall from first two essays, in addition to one or two more at this time) What subject should you start with first? - ANSWER Start with Recall and Comprehend Technical Information (35 questions) if allowed to. If not, then start with Solving mathematical questions (20 questions). Be mindful of questions with absolutes. What are some absolutes and why watch out for them? - ANSWER Examples of absolutes are "absolutely, always, forever, completely, infinite, never, only, sole, undeniable, or wholly". Absolutes or any sort of broad statements should be suspected as wrong. Recall and Comprehend Technical Information - ANSWER - Read one to four essays - 35 questions total (including questions for essays in back of test booklet) - notes can be written on the essay packet, NOT any other testing material. - 15 - 20 questions from these essays handed out in first 30 minutes. Recall and Comprehend Verbal and Visual Information: - ANSWER - 20 questions total - Watch 2 short videos - Answer 7 - 10 questions per video - Bases off of what is heard and seen in the videos. - NO NOTE TAKING DURING THIS TIME - Videos will only be played once. Gear Train, or commonly called "Transmission" - ANSWER Two or more gears working in a sequence, producing mechanical advantage through a gear ratio. Relationship between Speed, Torque, and Power: - ANSWER Power = 2pi x Speed (w) x Torque (nm)/ 60 Torque = 60 x Power (kW)/2pi x Speed (Rpm) Belt and Pulley Systems - ANSWER Two or more pulleys in common to a belt. If the pulleys are of differing pitch diameters, a mechanical advantage is realized. Doesn't depend on ratio of teeth as with gears and sprockets, only pitch diameter. What is a pulley (also called a "sheave" or "drum") - ANSWER A pulley is a wheel on an axle or shaft that is designed to support movement and change in direction of a belt or cable along its circumference. For a Rope and Pulley System that is a Block and Tackle, is characterized by: - ANSWER * If rope does not dissipate or store energy, then it's mechanical advantage is the number of parts of the rope that act on the load. - if the anchor knot is at the load ("A", "D", and "E") then mechanical advantage will be odd. (1:1, 3:1, 5:1, etc.) - if the anchor knot is at the anchor ("B", "C") then mechanical advantage will be even. (2:1, 4:1, 6:1, etc.)
