MECH324 - Homework Hints, Answers, and Extra Requirements

Homework 3 (Chapter 4)

TO ENHANCE YOUR LEARNING, PLEASE TRY TO WORK THE PROBLEMS FIRST WITHOUT LOOKING AT THE HINTS AND ANSWERS BELOW.

MAKE SURE YOU SATISFY ALL REQUIREMENTS LISTED BELOW AND IN THE ORIGINAL PROBLEM STATEMENTS (UNLESS INDICATED OTHERWISE BELOW).

NOTE - BECAUSE MOST ANSWERS ARE PROVIDED, IT IS VERY IMPORTANT THAT YOU SHOW ALL STEPS IN YOUR WORK.  THE GRADING WILL BE BASED ON THE COMPLETENESS, CLARITY, AND CORRECTNESS OF YOUR WORK, NOT JUST THE ANSWERS YOU PROVIDE.


4-2
[10 pts]
  • As with every problem, make sure you provide everything that is asked for (in this case, everything in parts "a" through "d").
  • Report RBA, not RAB (magnitude = 3.365).
4-7a
[15 pts]
  • Use the data in row "a" of Table P4-1.
  • You do not need to do the graphical solution.
  • Use equations 4.10b and 4.13 and report the values for all constants used in the equations.
  • Report answers for both the "open" and "crossed" positions.
  • θ4 = 117.3 degrees for "open"
  • θ3 = -115.2 degrees for "crossed"
  • Don't forget to report the Grashof condition.
4-10a
[10 pts]
  • Use the data in row "a" of Table P4-2.
  • You do not need to do the graphical solution.
  • Report answers for both "circuits."
  • θ3 = 180.1 degrees for circuit 1
  • d = -3.01 in for circuit 2
4-18a
[25 pts]
  • The linkage is in the "crossed" position.
  • Make sure your angle definitions are consistent with Figure 4-6.
  • Use equations 4.10b and 4.13 and report the values for all constants used in the equations.
  • the angle of link 4 in the first position (relative to the x axis) = -177.3 degrees
  • angular displacement of link 4 = 27.8 degrees
  • transmission angles: 87.5 degrees, 45.6 degrees
  • one toggle position: θ2 = 95.4 degrees
4-18f
[15 pts]
  • Generate the plots using MathCAD, Excel, or other computer graphing program. Do not use the SLIDER program provided with the book.
  • Plot one compete cycle (360 degrees) of crank motion.
4-19
[25 pts]
  • Define the motion of point Q, the top of the finger pushing the leftmost cylinder, where:
    p = distance between point A and point Q = 119.81;
    Δ = angle from AD to AQ = 37.54 degrees.
  • Use: e = vertical distance between point O2 and the top of the platen surface = 64.
  • The crank length is O2A (40), not O2B (i.e., in the 2nd sentence, O2B should be O2A).
  • Plot the height of point Q above the platen surface as a function of crank angle θ2.
  • crank angles where point Q is at the top of the platen surface: -13 degrees to 193 degrees (with the x-axis to the right) or 167 degrees to 13 degrees (with the x-axis to the left)
  • Measure the horizontal stroke of link 3 at the two points where point Q crosses the top of the platen surface, even though the point moves over a larger horizontal distance above the platen.
  • Ignore the sentence asking for the angular displacement of link 6 (i.e., you can ignore links 5 and 6).