Final answer:
To make a 30° bend using a bender and using travel to measure the angle, one should measure the travel distance post-bend with a ruler, and can check the precision using a protractor, similar to measuring vector magnitude and direction in physics.
Step-by-step explanation:
When making a 30° bend in an electric or mechanical bender and using the travel to measure the bend angle, the best procedure is to measure the travel to determine the bend angle. This means, after setting up your bending equipment, you perform the bend, and then you can use a ruler to measure the distance traveled by the bender to ensure that you've achieved the desired angle. Sometimes, bending charts or formulas can be used in conjunction to predict this travel. However, if precision is needed, a protractor is often used after the bend to check the angle and confirm accuracy. This process is analogous to using a ruler and protractor to measure the magnitude and direction of a resultant vector in physics, as vectors are often represented by both a magnitude and a direction, with the direction potentially measured using a protractor.