Vector Subtraction

Vector subtraction is no more difficult than vector addition.  To subtract one vector from another, simply take advantage of the fact that A - B = A + (-B).   In other words, rather than worrying about what subtraction means in vector algebra, simply add the negative of whichever vector you were trying to subtract.   The negative of a vector is easy to find -- it is nothing more than the original vector flipped around to point in the opposite direction.

Applet by Vladimir Sorokin

Place two vectors A and B on the grid and add them.  Now using your understanding of what constitutes vector subtraction, predict the resultant vector if you subtracted B froom A.   Now let the applet subtract them for you.  Was your prediction correct?

So now what?

What about cases where we need to precisely know the length and direction of the resultant vector?  In this situation, we need to rely on the component method, which is described in the next page.   But first, it would be a good idea to test your understanding of what we have learned so far.