Forces and Newton's Laws with vectors help

[delfam]

Homework Statement

One force of 60N and a second of 30N act on an object at point P. Graphically add the vectors and find the magnitude of the resultant when the angle between them is as follows.

a. 0 b. 30 c. 45 d. 60 e. 90 f. 180

Homework Equations

A-Sin A = B/Sin B = C/ Sin C
pythagorean theorum
F=ma

The Attempt at a Solution

I have no clue where to start

 

[LowlyPion]

Welcome to PF.

A force is a vector. [magnitude,direction]

The question is basically asking you to add vectors.

When 2 vectors are in the same direction then of course you just add the magnitudes and the result is the sum in the same direction.

That's a) your 0° answer directly.

b) asks you to add 2 vectors that are 30° to each other, so ...

 

[delfam]

so how would i find 30 degrees, do I use the laws of sine or cosine

 

[LowlyPion]

so how would i find 30 degrees, do I use the laws of sine or cosine

The Law of Cosines should do it.

To add only two vectors, use the law of cosines. Draw the vectors head to tail. Then the resultant is the other side of the triangle.

c² = a² + b² - 2 ab cos C,
where a, b, and c are sides and angle C is opposite side c.

http://quarknet.fnal.gov/toolkits/ati/vectors.html