Vectors & Forces: Find Resultant Direction & Magnitude

In summary, the problem involves finding the direction and magnitude of the resultant of two forces given a specific angle. The coordinates of the first vector are <220,0> and the coordinates of the second vector are <[150√(3)]/2,75>. After adding the two vectors, the magnitude of the resultant vector is found to be 590.63 Newtons, which is incorrect. Upon correcting the error in the x-component calculation to be [440+150√(3)]/2, the magnitude is found to be 357.85 Newtons, as stated in the book's answer section.
  • #1
themadhatter1
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Homework Statement



If θ=30 degrees find the direction and magnitude of the resultant of these forces.
[PLAIN]http://img194.imageshack.us/img194/7899/image2iw.jpg

Homework Equations





The Attempt at a Solution



Ok, so I know I have to add both of the vectors. I need to find the coordinates to do so. The first vector's coordinates must be <220,0>. Next I need to find the second vector's coordinates:

x=150cos30
x=[150√(3)]/2
y=150cos30
y=75

so the second vector has the coordinates <[150√(3)]/2,75>

If you add the second and the first vectors you get <[590√(3)]/2,75>

Then I found the magnitude of this new vector to be 590.63 Newtons. However, this is wrong because the book's answer section says the magnitude should be 357.85 Newtons.

If i go on to find the direction that also turns out wrong. What am I doing wrong?
 
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  • #2
The x-component of your vector sum is 590*sqrt(3)/2, which is about 510. That is incorrect, and is too large (you should get about 350). Take a look again at your calculation for this component.
 
  • #3
Ahh. Thanks, I found my error. The x component should be:

[440+150√(3)]/2
 

FAQ: Vectors & Forces: Find Resultant Direction & Magnitude

1. What is a vector?

A vector is a mathematical representation of a physical quantity that has both magnitude and direction. It is often represented by an arrow, with the length of the arrow representing the magnitude and the direction of the arrow indicating the direction.

2. How do you find the resultant of two or more vectors?

To find the resultant of two or more vectors, you must first determine the direction and magnitude of each vector. Then, use vector addition to add the vectors together. The resultant will be the vector that represents the combined effect of all the individual vectors.

3. What is the difference between a scalar and a vector?

A scalar is a physical quantity that only has magnitude and is represented by a number. Examples of scalars include speed, mass, and temperature. A vector, on the other hand, has both magnitude and direction and is represented by an arrow. Examples of vectors include displacement, velocity, and force.

4. How do you calculate the magnitude of a vector?

The magnitude of a vector can be calculated using the Pythagorean theorem, where the magnitude is equal to the square root of the sum of the squares of the individual components (x and y for 2D vectors, x, y, and z for 3D vectors). Alternatively, you can use the magnitude formula: |v| = √(vx2 + vy2 + vz2).

5. Can the direction of a vector be negative?

Yes, the direction of a vector can be negative. This is often seen in 2D vectors, where angles are measured counterclockwise from the positive x-axis. The direction can also be negative in 3D vectors, where angles are measured relative to a specific plane or axis.

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