MA331 Wind Tunnel notes
When the wind tunnel reading is E microvolts, the corresponding drag force, in pounds, is
D = 0.089*E + .0052.
The Drag force is given by
F = 1/2*rho*v2*pi*R2*CD,
where rho =.002377 slugs/ft3,
v is the velocity in ft/s,
R is trhe radius of a baseball = 3/(8pi) ft,
CD is the drag coefficient.
The conversion from miles per hour to feet per second is
(fps)= (22/15)*(mph).
Thus, 15 miles per hour is equal to 22 feet per second.
We may also solve this equation for the drag coefficient,
CD = 2F/(rho*v2*pi*R2).
Each sample took 400 readings.
If you have any questions, please
e-mail me.
The temperature started at 21 degrees C and ended at 22.3 degrees C.
The barometric pressure was 1027 mbar (30.37 inHg).
First, the readings without the baseball
| Velocity(mph) | Drag(microvolts) | St.Dev.(microvolts) |
| 0 | 1.337235 | 0.6140914 |
| 62 | 21.61153 | 19.03719 |
| 93 | 50.44101 | 19.82567 |
| 103.5 | 63.06803 | 21.64098 |
| 121 | 87.23601 | 21.81997 |
| 139 | 113.2876 | 21.09844 |
Next, the readings with the baseball attached
| Velocity(mph) | Drag(microvolts) | St.Dev.(microvolts) |
| 0 | 1.891542 | 0.5853375 |
| 61 | 44.81271 | 22.52351 |
| 84.5 | 80.44364 | 25.50062 |
| 93 | 100.3694 | 30.94699 |
| 100 | 114.9753 | 29.59025 |
| 113.5 | 147.6635 | 29.87023 |
| 121 | 168.5192 | 34.53888 |
| 131 | 194.4014 | 38.32475 |
| 141 | 219.9257 | 37.55017 |
| 159 | 253.6635 | 42.16171 |
| 0 | -8.043830 | 3.447944 |
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