# Friction Problem

## ES 301 Assignment 4

Work Problem 8.15, page 410, in Beer and Johnston Statics, sixth edition in the usual way. Then, using either Notepad in Windows 95 or Emacs in Unix, write a Matlab program to find the sliding angle for weights of block A ranging from 0 to 60 pounds at 2-lb intervals. Also, plot the sliding angle vs. the weight of block A as shown below. Run your program in Matlab. Be sure to program your name, date, and subject with lines such as:

```    % print the results
fprintf('\n   Friction problem, Beer 8.15')
fprintf('\n   Your name, ES 301, ')
disp(date)```
Also, be sure to use vectors for weight A (a), the angle (ang), and the absolute value of the angle (aang) since the angle is negative when A weighs more than B.
```    a = 0:2:60       % weight a has several values
```
Don't use a loop to define the vector of angles. Just use a single statement. You will have to use a ./ for division.
```    ang = atan(2*mu*a ./(
```
Use the f format to control the number of displayed digits. Print the results with a heading in a table that starts like as:
```        Weight    Angle,
A, lb   degrees
1    0      0.00
2    2      1.23
3    4      2.64
```
Copy the output data from the screen and paste it into the bottom of your source program. Adjust the number between the % and . to align the decimal points. Print your source program with the appended output.

Make a plot of absolute value of angle vs. weight of A with title, grid, and x and y labels using the plot, title, xlabel, ylabel, and grid commands. Print the plot. Make a cover page describing what you did.

Staple the cover page, printouts of your source code, and the plot to your solution obtained by the conventional method and turn it in as usual.

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Last revised: March 17, 2000