Inside Collection (Course): Freshman Engineering Problem Solving with MATLAB

Summary: This module provides a tutorial introduction to graphing data in m-file environments.

One of the reasons that m-file environments are extensively used by engineers is their capability to provide graphical representations of data and computed values. In this module, we introduced the basics of graphing data in m-file environments through a series of examples. This module uses some fundamental operations on vectors that are explained in Vectors and Arrays in M-File Environments.

The table below shows speed as a function of distance for a braking Dodge Viper decelerating from 70MPH to 0MPH.

This data was not measured; it was computed using the stopping distance reported for a Dodge Viper and assuming constant deceleration. Thus, it may not accurately reflect the braking characteristics of a real Dodge Viper.

Distance (ft) | Velocity (ft/s) |

0 | 102.7 |

29.1 | 92.4 |

55.1 | 82.1 |

78.0 | 71.9 |

97.9 | 61.6 |

114.7 | 51.3 |

128.5 | 41.1 |

139.2 | 30.8 |

146.9 | 20.5 |

151.5 | 10.3 |

153.0 | 0.0 |

```
dist = [0 29.1 55.1 78.0 97.9 114.7 128.5 139.2 146.9 151.5 153.0]
vel = [102.7 92.4 82.1 71.9 61.6 51.3 41.1 30.8 20.5 10.3 0.0]
plot(dist,vel)
```

```
xlabel('Distance (ft)')
ylabel('Velocity (ft/s)')
title('Velocity vs Distance for the Dodge Viper')
```

After creating a figure, you may wish to insert it into a document. The method to do this depends on the m-file environment, the document editor and the operating system you are using.

To paste a figure into a Word document on Windows, pull down the *Edit* menu of the window of the MATLAB figure you wish to paste, and select *Copy Figure*. Then go to the Word document into which you wish to insert the figure and use the paste command.

Repeat Example 1 using the following data for a Hummer H2:

As in Example 1, this data was not measured; it was computed using the stopping distance reported for a Hummer H2 and assuming constant deceleration.

Distance (ft) | Velocity (ft/s) |

0 | 102.7 |

46.3 | 92.4 |

87.8 | 82.1 |

124.4 | 71.9 |

156.1 | 61.6 |

182.9 | 51.3 |

204.9 | 41.1 |

222.0 | 30.8 |

234.2 | 20.5 |

241.5 | 10.3 |

244.0 | 0.0 |

Figure 3 shows the graph of the Hummer H2 stopping data.

An m-file environment can also be used to plot functions. For example, the following commands plot

```
x = 0:0.1:2*pi;
y=cos(x)
plot(x,y)
xlabel('x')
ylabel('cos(x)')
title('Plot of cos(x)')
```

The module Exercises for Basic Mathematical Operations describes how to compute the terminal velocity of a falling sky diver. Plot the terminal velocity as a function of the sky diver's weight; use weights from 40kg to 500kg.

In electrical circuit analysis, the equivalent resistance

In an experiment, a small steel ball is dropped and videoed against a checkered background. The video sequence is analyzed to determine the height of the ball as a function of time to give the data in the following table:

Time (s) | Height (in) |

0.0300 | 22.0 |

0.0633 | 21.5 |

0.0967 | 20.5 |

0.1300 | 18.8 |

0.1633 | 17.0 |

0.1967 | 14.5 |

0.2300 | 12.0 |

0.2633 | 8.0 |

0.2967 | 3.0 |

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