Finding a vector using scalar and vector projections

In summary, the problem is to determine a vector and its scalar projection given a specific vector projection and scalar projection. The necessary equations for vector and scalar projections are provided. The attempt at a solution involved finding a vector using the scalar projection equation, but the problem lies in the algebraic manipulation.
  • #1
user8899
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0

Homework Statement



Determine the vector(s) whose vector projection on u =< 1,2,2 > is v =< 3,6,6 > and its
scalar projection on w =< 1,1,1 > is √3.

Homework Equations


Vector Projection of b onto a: (|b.a| \ |a|) * (1/ |a|) * a
Scalar Projection: (|b.a| \ |a|)


The Attempt at a Solution


First started by finding the vector <a,b,3-b-c> (using the scalar projection equation), but don't know what else to do from there. Help please?
 
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  • #2
welcome to pf!

hi user8899! welcome to pf! :smile:
user8899 said:
First started by finding the vector <a,b,3-b-c> (using the scalar projection equation) …

isn't the scalar projection just the magnitude of the vector projection? :wink:
 
  • #3
Hi, Thank you!

well I substituted <a,b,3-b-c> into the vector projection equation, but I think my problem is the algebra... I'm not sure
 
  • #4
what is your vector projection equation? :smile:
 

1. What is the difference between scalar and vector projections?

The scalar projection is a scalar value that represents the length of the vector projection onto another vector. The vector projection is a vector that is parallel to the other vector and has the same direction and magnitude. In other words, the scalar projection gives the magnitude of the vector projection.

2. How do you find the scalar projection of a vector?

To find the scalar projection of a vector onto another vector, you first need to find the dot product of the two vectors. Then, divide the dot product by the magnitude of the second vector. The result will be the scalar projection of the first vector onto the second vector.

3. How do you find the vector projection of a vector?

To find the vector projection of a vector onto another vector, you first need to find the scalar projection of the vector onto the other vector. Then, multiply the scalar projection by the unit vector in the direction of the second vector. This will give you the vector projection of the first vector onto the second vector.

4. Can you explain the geometric interpretation of scalar and vector projections?

The scalar projection represents the length of the shadow that the vector casts onto another vector. The vector projection represents the actual shadow that is cast onto the other vector. In other words, the scalar projection is the magnitude of the vector projection.

5. How are scalar and vector projections used in real life?

Scalar and vector projections have many practical applications in physics, engineering, and computer graphics. They are used to calculate forces, velocities, and accelerations in various systems. For example, in computer graphics, vector projections are used to create realistic shadows and reflections in 3D environments.

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