Screen output
The text shown in Figure 3 should appear in your browser window when the html file is opened in your browser.
| Figure 3 . Screen output for Listing #2. |
|---|
Start Script
Time for leg A = 0.30 secondsTime for leg B = 0.33 seconds
Displacement magnitude = 25.00 feetDisplacement angle = 98.13 degreesTotal time = 0.63 seconds
Average velocity magnitude = 39.47 feet/secondAverage velocity angle = 98.13 degrees
End Script |
Analysis of the code
In this exercise, the puck makes a journey across the ice consisting of two sequential legs in different directions with different magnitudes ofvelocity. Although each leg involves motion along a line, the total trip is not along a line.
The objective of the script is to
- Compute and display the time required to traverse each leg of the trip based on the given information.
- Compute and display the magnitude and the angle of the displacement from start to finish.
- Compute and display the time required to complete the entire trip, which is the sum of the times from both legs.
- Compute and display the magnitude of the average velocity as the magnitude of the displacement divided by the total time.
- Recognize that the angle of the average velocity is the same as the angle of the displacement.
The getAngle function
The code in Listing 2 begins with the getAngle function that we developed and used an earlier module. The purpose of the function is to receive the adjacentand opposite side values for a right triangle as parameters and to return the angle in degrees in the correct quadrant.
I explained this function in an earlier module and won't repeat that explanation in this module.
Compute the time for each leg
Following the definition of the getAngle function, Listing 2 computes the time required to traverse each leg of the trip. For variable naming purposes, the two legs are identified as A and B.
Variable names that end with "mag" contain vector magnitudes. Variable names that end with "ang" contain vector angles. Variable names that endwith "vel" contain the magnitudes of straight-line, uniform velocities.
The time to complete each leg of the trip is computed by dividing the magnitude of the displacement vector for that leg by the magnitude of thestraight-line velocity for that leg. The resulting times have units of seconds, and are saved in the variables named timeA and timeB .
The overall displacement
The magnitude and angle of the overall displacement for the two-leg trip (identified by the variables named vecResultMag and vecResultAng respectively) are computed using procedures that were explained in an earlier module. Therefore, I won't repeat that explanation inthis module.
The magnitude of the overall displacement is stored in the variable named vecResultMag , and the angle for the overall displacement is stored in the variable named vecResultAng .
The total time
The total time for the trip, identified by the variable named totalTime , is computed as the sum of the times for the individual legs.
Magnitude of the average velocity vector