Question: How do I accurately calculate the resultant of 3 vector inputs?

[Chapman2233]

I have just been given my first assignment and I have calculated all the data, but there is no clear writing that says what answer they want.

Im sorry if this is a stupid question but i have just started physics, anyway i have been given three forces which had to be converted to cartesian co-ordinates from the given data which was a value in kN and an angle (i checked both answers as i did them both on autocad).

Now the resultant i got does not seem right, and i am not sure how to finish off my answer as i have to draw it on grid paper.

Sorry if this is vague, its just hard to explain where i am right now, I will upload a summation of the questions and my data.


Thanks again for any help.

 

[gneill]

I have just been given my first assignment and I have calculated all the data, but there is no clear writing that says what answer they want.

Im sorry if this is a stupid question but i have just started physics, anyway i have been given three forces which had to be converted to cartesian co-ordinates from the given data which was a value in kN and an angle (i checked both answers as i did them both on autocad).

Now the resultant i got does not seem right, and i am not sure how to finish off my answer as i have to draw it on grid paper.

Sorry if this is vague, its just hard to explain where i am right now, I will upload a summation of the questions and my data.


Thanks again for any help.

Hi Chapman2233, Welcome to Physics Forums.

Your work looks fine right up to the point where you calculate the angle of the resultant. You have to be careful applying the atan function because it doesn't take into account the signs of the numerator and denominator and how they determine the quadrant for the angle. If your software has an atan2() function, I would recommend using that. Otherwise, take particular care using the atan() function to sort out the proper quadrant.