# Homework Help: Add forces as vectors help - Thanks!

1. Dec 6, 2011

### nukeman

1. The problem statement, all variables and given/known data

I am not understanding this. This is the question, and the correct solutions for the question I need help with.

I really dont understand how to get the answer here! Can anyone help me? First steps?

Question:

2. Relevant equations

3. The attempt at a solution

2. Dec 6, 2011

### technician

Are you confident with the idea that you have 2 forces which are vectors.
In the first case the vectors (20N and 15N) are at 90 degrees. To find acceleration you divide F by m (5kg) giving 2 acceleration vectors 4 and 3 at 90 degrees.
You need to find the resultant of these 2 perpendicular vectors (pythagoras !!!)
In the second case the logic is the same but the angle is not 90 degrees.
Is this any help?

3. Dec 6, 2011

### nukeman

I understand how to get (4i + 3j) but how did they eventually come up with 5 m/s^2 at 36.9 degreeS?

4. Dec 6, 2011

### DrewD

The magnitude of the vector comes from the pythagorean theorem by treating the two vectors as perpendicular sides of a triangle. Trig is the best way to get the angle. How's your trig?