- #1
- 10
- 0
Homework Statement
In photo:
https://gyazo.com/6348b5ffe368852ee9868a2ba0dd7e38
Homework Equations
In image
The Attempt at a Solution
In the boxes
Where did I go wrong with the angle calculation?
Thanks
Help with Vector Addition Problem
- Thread starter Josh Eiland
- Start date
In photo:
https://gyazo.com/6348b5ffe368852ee9868a2ba0dd7e38
In image
In the boxes
Where did I go wrong with the angle calculation?
Thanks
Answers and Replies
- #2
- 907
- 88
I don't know, you didn't show the Calc.
- #3
- 10
- 0
https://gyazo.com/efc009de2080feedea420d6b2a5edab4
Triangle on the right shows how I calculated -10° angle by using tan-1(-3.2/17.4), -3.2 being the change in y and 17.4 change in x after I added the vectors.
- #4
- 907
- 88
Can't follow your work. Your original post gives the answer as 350. How did you come up with this number?
Last edited:
- #5
- 10
- 0
I calculated the angle as -10°, but since the question asked for the angle counter-clockwise from the x axis, I thought it would be correctly expressed as 350.
- #6
- 907
- 88
-10 degrees measured from what?
- #7
- 10
- 0
From the positive x axis.
- #8
- 605
- 6
Okay where did you get the -10 degrees from?
You can find the coordinate of the player's position through your vectors. After that you can simply use geometry to determine the ccw angle, after that, 360 - positive angle = clockwise angle. The program may not want to accept negative angles, try the positive equivalent between 0 and 360.
You can find the coordinate of the player's position through your vectors. After that you can simply use geometry to determine the ccw angle, after that, 360 - positive angle = clockwise angle. The program may not want to accept negative angles, try the positive equivalent between 0 and 360.
- #9
- 10
- 0
https://gyazo.com/efc009de2080feedea420d6b2a5edab4
Triangle on the right shows how I calculated -10° angle by using tan-1(-3.2/17.4), -3.2 being the change in y and 17.4 change in x after I added the vectors.
- #10
- 10
- 0
And yes, that's how I got 350° counter-clockwise. By doing 360 minus the clockwise angle (360-10).
- #11
- 907
- 88
I think if you draw yourself a picture you will see that it can't be -10 degrees from the +ve x-axis.
- #12
- 10
- 0
I got -10 from the X-axis counter-clockwise when drawing a picture, as I've explained. Do you have a better answer or suggestion?
- #13
- 907
- 88
I could not understand your drawings. So my suggestion is to redraw a simple picture that summarizes the vectors and shows the -10 degrees.
- #14
- 605
- 6
From this image, find the vector P.
- #15
- 10
- 0
That wouldn't make sense, as the angle from initial to final points would be from the top of the red line on the y-axis to the final spot, not from the origin.
From this image, find the vector P.
- #16
- 10
- 0
I calculated the final point (17.4, -3.2) and drew a line from the origin (0,0) to this point, creating a triangle with the x and y segments. Using Pythagorean theorem I calculated the magnitude of this vector 17.7
I then used inverse tangent to find the angle -10°
- #17
- 907
- 88
Ok, I follow you now. I think you got it right. Maybe a small rounding error. Try and see if 349.6 works.
- #18
- 10
- 0
Tried it, didn't work. I think the teacher probably just put the answer in wrong accidentally. Will ask tomorrow. Thanks for help.
- #19
- 605
- 6
That is not the answer that I am getting at all.
I am getting a positive angle of 24.213 degrees counter-clockwise.
Again, if you're not showing your calculations it's impossible for us to tell you where you're going wrong.
Your y-coordinate is wrong. The point is in the first quadrant.
Bx=11.3137
By=11.3137
Cx=6.0622
Cy=3.5
Therefore the resultant vector is
r=[Bx+Cx,By-Cy]
I am getting a positive angle of 24.213 degrees counter-clockwise.
Again, if you're not showing your calculations it's impossible for us to tell you where you're going wrong.
Your y-coordinate is wrong. The point is in the first quadrant.
Bx=11.3137
By=11.3137
Cx=6.0622
Cy=3.5
Therefore the resultant vector is
r=[Bx+Cx,By-Cy]
- #20
- 907
- 88
I got the same answer as the OP.
- #21
- 605
- 6
OP calculated his final Y-coordinate as a negative, it doesn't make sense from the given picture assuming that the Y-axis goes along vector A and the X-axis goes through the bottom corner.