1. Sep 23, 2004

Haftred

One of my review questions is the following:

"A box is pulled along the floor by a horizontal force of 35 N. Another force acts concurrently on the box with a force of 25 N at an angle of 40 degrees above the horizontal in the same direction as the first force. What is the sum of the two vectors?"

I got the magnitude of the vector to be 56 N by finding the square root of the horizontal and vertical components respectively squared. However, how does one find the angle. I know I need to calculate the inverse tangent of something - but what?

2. Sep 23, 2004

christinono

Try breaking the vectors down into their x and y components. Then find the sum of the x components, then the sum of the y components. Then, draw a triangle with these vector sums and use trig to find the resultant vector.

3. Sep 23, 2004

Haftred

thanks...I'll definetely do better on the exam now

4. Sep 23, 2004

christinono

5. Sep 23, 2004

Tom McCurdy

note be sure to add in the extra degres when using a triangle for trig
you can solve for the angle but then you may need to add/subtract 90,180,270,360

Last edited: Sep 23, 2004
6. Sep 23, 2004

Tom McCurdy

example
--------------=--------------------
--------------=-------------------- ROUGH DRAWING
--------------=--------------------
--------------=-------------------- VECTOR ONE= postive x
--------------=-------------------- VECTOR TWO= negitive y
--------------=--------------------
============AAAAAAAAAAAAAAA
--------------A-A------ If you solve for this angle and you have
--------------A-- A----------counterclockwise movement then you must
--------------A----- A------- subtract 360 to get angle
--------------A-------- A
--------------=-------------------
--------------=-------------------
--------------=-------------------

I hope this makes sense
i know it is very rough sketch