Question

Vector A⃗ , which is shown in the figure, has a magnitude of 10 and a direction angle of 60º. What is the magnitude and direction angle (as measured counterclockwise from the positive x-axis) of −A⃗ /2?
http://session.masteringphysics.com/problemAsset/1445605/2/PLCQ_ArtMs_Topic02_Q03_v2.jpg
-5, 60º
5, 240º
5, -30º
-5, -30º
-5, 240º

Answer 1

Okay! So, you have \(\vec A\). Do you know what happens when you divide it by \(2\)?

Answer 2

goes to 5

Answer 3

Right! It's \(\sf length\) becomes \(5\).

And now, what happens when you make it negative?

Answer 4

its below the x axis

Answer 5

It really makes the vector point in the opposite direction.

Answer 6

okay

Answer 7

That is a \(180^\circ\) rotation. The magnitude of a vector is always positive. So you're magnitude goes to \(5\) and your angle goes to... what?

Answer 8

240

Answer 9

Right! \(180^\circ+60^\circ=240^\circ\)

Answer 10

So, now you have your answer!

Answer 11

thanks

Answer 12

You're welcome! :)