Help Solving Vectors with Angles - Newbie in Physics

[bh373]

Hello, first timer here. not sure if this should be in physics section or not.. anywayss

I have this question, 2-4 that i have to do for homework but i can't seem to set up the vectors in the correct way to solve b/c the axis/angles are really throwing me off. I'm new at this trying to learn it. i took a picture since its easier to understand than me trying to describe through words.

please help me determine the magnitude of resultant force and its direction.

sorry for my scribbling on the diagram, and please ignore the lightly shaded lines :) THANK YOU

 

[SteamKing]

For your problem, ignore the axis v except for using it to find the angle between F2 and the u-axis. The problem wants you to find the resultant F1 + F2 relative to the u-axis.

 

[bh373]

thanks for the response. so you're saying i need the v-axis to find the angle of F2 to the u-axis? wouldn't that just be 60? i don't see why i'd need the v-axis..

 

[bh373]

basically what i cannot understand is :

if the resultant force is somewhere between the U and V axis, how am i supposed to use sine/cosine when the angle will not be 30* or 45*

thanks

 

[SteamKing]

Sine and Cosine are defined for angles 0-360 degrees. Are you having problems calculating trig functions? Remember, you are using a computer to post your homework questions. You can calculate sine and cosine directly or find a table of values for these functions.

 

[bh373]

no, i know the values of sin/cos for the commonly used angles. What I am trying to say is while looking at the diagram, wouldn't the resultant force that it is asking me to find the magnitude of, be somewhere between the U and V axis...where angles are not defined? am i just drawing this diagram wrong? for some reason i understand questions involving 3 axis better than these ones that are supposed to be easy...ughhhh

 

[SteamKing]

Pretend the diagram as shown was actually drawn as a mirror image.
Take Vector F1 = 200 lbs < -45 deg
Vector F2 = 150 lbs < +60 deg

Calculate the horizontal and vertical components of F1 and F2 and find the Resultant.

 

[bh373]

thank you for the response. I put some time into figuring out the correct answer, this comes much easier now. All i had to do was law of cos to solve for Fr then law of sines to figure out the angle. much easier. thank you