How Do You Calculate Change in Velocity?

[sphykik]

[SOLVED] Velocity Problem

Homework Statement

A motor scooter travels east at a speed of 12 m/s. The driver then reverses direction and heads west at 16 m/s. What was the change in velocity of the scooter?

Homework Equations

The Attempt at a Solution

Looking at this problem, I thought it was extremely easy, but I seem to not be getting the right answer, haha (our homework is submitted electronically). Anyways, since you only have components in the x direction I thought I could just add the velocities. I figured the driver would move +12 m/s, and then -16 m/s. That would result in a change of 4, or negative 4 if you count the direction... But that's not correct, so I must be missing something!

Thanks in advance for the help,
Damian

 

[Kurdt]

Since we dealing in velocities they have a magnitude and direction. We can show the direction of travel in one dimension by choosing one direction to be positive. If we choose east to be positive then his velocity to the east is 12m/s and his velocity to the west is -16m/s. What is the difference between these two numbers? Remember that the difference of two numbers A and B is given by |A - B|.

 

[sphykik]

Thanks, I got an answer of 28, and it is correct!