How Do You Calculate the Magnitude of Vector C in Vector Subtraction?

  • Thread starter Thread starter x31fighter
  • Start date Start date
  • Tags Tags
    Physics Vector
Click For Summary

Homework Help Overview

The discussion revolves around calculating the magnitude of vector C resulting from the vector subtraction C = B - A, where vectors A and B are defined with specific magnitudes and angles. The problem involves understanding vector components and their correct application in subtraction.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to find the magnitude of vector C using trigonometric methods to resolve vectors A and B into their components. There is a question raised about the applicability of the cross product in this context.

Discussion Status

Some participants have provided feedback on the correctness of the vector components, indicating that the original poster's calculations for vector B were initially incorrect but were later corrected. There is an ongoing exploration of the appropriate methods for vector subtraction.

Contextual Notes

Participants are discussing the implications of angles measured from different axes and the importance of correctly identifying these angles in vector calculations. There is a mention of homework constraints regarding the methods allowed for solving the problem.

x31fighter
Messages
4
Reaction score
0

Homework Statement


C = B - A
A = 16 Units
A-theta = 42 degrees from the y-axis
Ai is pointing in second quadrant

B = 7 units
B-theta = 31 degrees from the x-axis
B is pointing in the third quadrant

Homework Equations




The Attempt at a Solution


I am suppose to find the magnitude of C from the components given. When I attempted it, I did it using trigonometric. That got marked wrong. Just a random question, am I able to do it using cross-product or something like that?

Va-x = -16*sin(42)
va-y = 16*cos(42)

Vb-x = - 7.0*sin(31)
Vb-y = - 7.0cos(31)

Did Pythagorean theorem and combined the x and y and got the following result:
C =15.45
 
Physics news on Phys.org
C is also a vector, so you need to come up with an angle as well as the correct magnitude.

Va_x and Va_y are correct.
Vb_x and Vb_y are incorrect. 31 deg. is from the x, not the y, axis ...
 
Oops...

I fixed that. I am getting the correct answer now.
 
Vector subtraction has nothing to do with the cross product.
 

Similar threads

Finding Vector C: Magnitude and Angle Calculation
  • · Replies 5 ·
Replies
5
Views
4K
Vector Subtract Given Magnitude
  • · Replies 6 ·
Replies
6
Views
2K
Calculating magnitudes of vectors
  • · Replies 1 ·
Replies
1
Views
2K
X and Y components of a vector using a graph of speed/time
  • · Replies 2 ·
Replies
2
Views
2K
Solve for vectors needed to cancel out given sets of forces
  • · Replies 3 ·
Replies
3
Views
2K
Calculate electric force using Coulomb's law (vector components are the struggle)
  • · Replies 3 ·
Replies
3
Views
2K
Adding Vectors-Calculating Magnitude and Location
  • · Replies 6 ·
Replies
6
Views
2K
Finding the magnitude of a vector B given vector C
  • · Replies 5 ·
Replies
5
Views
2K
Basic Vectors: If vector A and C are given what is the magnitude of vector B?
  • · Replies 3 ·
Replies
3
Views
5K
How do you find the third vector C in vector addition problems?
  • · Replies 2 ·
Replies
2
Views
2K