Solve Vector Decomposition Homework: F=-11j, v=-i-5j

Click For Summary
SUMMARY

The discussion focuses on solving a vector decomposition homework problem involving a force vector F = -11j and a velocity vector v = -i - 5j. The participants successfully calculated the parallel component of F to v as ProjvF = <-2.115, -10.576> and identified the orthogonal component as OrthvF = <2.115, -0.424>. The work done by the force through the displacement was calculated as W = 4.664. Participants clarified that the correct approach for calculating work involves using the perpendicular component of the force.

PREREQUISITES
  • Understanding of vector notation and operations
  • Familiarity with dot product calculations
  • Knowledge of vector projection and orthogonal components
  • Basic principles of work in physics
NEXT STEPS
  • Study vector projection techniques in depth
  • Learn about orthogonal vectors and their applications
  • Explore the concept of work done by forces in physics
  • Practice problems involving force and displacement vectors
USEFUL FOR

Students studying physics, particularly those focusing on vector mechanics, as well as educators looking for examples of vector decomposition problems.

Turbodog66
Messages
13
Reaction score
0

Homework Statement



The force on an object is F = -11j. For the vector v =-i-5j, find:

1. The component of F parallel to v
2. The component of F perpendicular to v
3. The work, W, done by force F through displacement v

Homework Equations



ProjvF = v dot F/ |v|2
OrthvF = F - ProjvF
W = D dot F

The Attempt at a Solution



F = < 0, -11> v = < -1, -5>

1.
ProjvF = -1(0) + -5(-11) / 12 + -52 = 55/26<-1, -5>
ProjvF = <-2.115, -10.576>

2.
OrthvF = < 0, -11> - <-2.115, -10.576> = 0 + 2.115 , -11 +10.576 = <2.115, -0.424>
OrthvF = <2.115, -0.424>

3.
W = <2.115, -0.424> dot < 0, -11> = 2.115(0) + -0.424(-11) = 4.664
W = 4.664I am told that step 1 is correct, and the first value in step 2 is correct. I cannot figure out what I am missing on part 2, which is ultimately messing up step 3. Any help would be appreciated.
 
Physics news on Phys.org
In 3 you don't do ##\vec v\cdot\vec F## but you use the one that's perpendicular.
In 2 I don't see what's wrong.
 
  • Like
Likes   Reactions: Turbodog66
BvU said:
In 3 you don't do ##\vec v\cdot\vec F## but you use the one that's perpendicular.
In 2 I don't see what's wrong.
Thanks, I see what I did wrong on part 3. Part 2 after redoing it again was expecting -0.42307, I rounded too soon it seems
 

Similar threads

Replies
2
Views
2K
Replies
9
Views
2K
  • · Replies 8 ·
Replies
8
Views
2K
Replies
4
Views
2K
Replies
7
Views
2K
  • · Replies 1 ·
Replies
1
Views
4K
Replies
5
Views
2K
  • · Replies 8 ·
Replies
8
Views
2K
Replies
8
Views
2K
  • · Replies 11 ·
Replies
11
Views
2K