ENGR 8
Assignment 8 Chapter 5.5-5.7
Due: next wed
You must solve 2 problems completely in Matlab/Freemat. You also may use Matlab as an equation solver.
Print out and staple your matlab .m file for two problems to your homework.
Part 1. Assisted Problem Solving -- 2 points each
Plan:
1) Draw the FBD, adding weight at center
2) All forces are vertical
3) Set up EofE and solve
Sum of Z forces=0
Sum of Moments about any corner
or edge = 0
Proper choice of equation can simplify solution
Use scalar moment equations
Sum Ma_x, Sum Ma_y, Sum Ma_z = 0 etc
PLAN:
1) Draw FBD, add weight at center
2) There are 5 reaction forces (2 at B, 3 at A)
3) Label reactions at A and B
4) Set up E of E and solve for the 5 unknowns. You
may set up any of the equations below:
a. Sum Fx, Sum Fy, Sum Fz = 0
b. Sum Ma_x, Sum Ma_y, Sum Ma_z = 0
c. Sum Mb_x, Sum Mb_y, Sum Mb_z = 0
Use scalar moment equations
PLAN:
1) Draw FBD
2) Assume there are 2 reaction forces at each
bearing (the moments should not be needed)
3) Set up E of E and solve
a. Sum Fx, Sum Fy, Sum Fz = 0
b. Sum Ma_x, Sum Ma_y, Sum Ma_z = 0
4) Moments around other points may be helpful in
arriving more quickly at a solution on paper.
5) If using Matlab, just set up a matrix and solve
PLAN:
1) Draw FBD of table top only, apply W at center
2) Add an external force P at one of the
unsupported corners
3) Draw an axis line from the leg in the mid-edge
to the corner leg opposite P
4) Tipping point occurs when the
moment about axis line due to P +
moment about axis line due to W = 0
(and reaction at leg opposite P=0, no weight)
This problem can’t be solved in Matlab
Part III. Unassisted Problem Solving -- 3 points each