# Homework Help: How much does the raft move with change of position?

1. Apr 14, 2015

### ninesixfive

• HW Template missing as it was moved from another forum
heres the problem...

and i figured out part a but dont understand how to get the second part, here is what i have done...

my question is should the angle be from the point of origin? what im getting is -2.12 meters in a direction of -45 degrees. is this correct? I'm using x2-x1/y2-y1 to get 1.5/-1.5 then using Pythagorean to get the distance of shift and using arctan(-1.5/1.5) to get the -45 ?

2. Apr 14, 2015

### Staff: Mentor

The vector does not need a reference point, just a reference direction. Relative to the x-axis should be fine. Or relative to some other direction which you clearly describe. Like "from the center towards the new position of [...]".
The magnitude should be positive.

3. Apr 15, 2015

### ninesixfive

So could I say the raft moves 2.12 meters in a direction of 135 degrees when viewing form above?

4. Apr 15, 2015

### Staff: Mentor

If you clarify 135 degrees relative to what, sure.

5. Apr 15, 2015

### ninesixfive

relative to the point of origin (bottom left corner)... looking at it from above it would move into the the third quadrant , of course the raft would stay square to the x and y axis