Initial value problem-application (multivariable calculus)

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SUMMARY

The discussion focuses on solving an initial value problem in multivariable calculus involving vector functions. The user seeks clarification on determining the constants in the velocity and position equations derived from integration. The solution involves calculating the velocity vector as ##v(t) = -\sin t \hat i + \cos t \hat j + \hat k## and the position vector as ##r(t) = \cos t \hat i + \sin t \hat j + t \hat k## by applying initial conditions to find the constants. The final forms of the vectors are confirmed through substitution and integration processes.

PREREQUISITES
  • Understanding of vector calculus concepts, specifically vector functions.
  • Familiarity with integration techniques in multivariable calculus.
  • Knowledge of initial value problems and their applications.
  • Ability to work with constant vectors in the context of vector equations.
NEXT STEPS
  • Study the process of integrating vector functions in multivariable calculus.
  • Learn about initial value problems and their significance in physics and engineering.
  • Explore the application of constant vectors in solving differential equations.
  • Practice problems involving velocity and position vectors in different contexts.
USEFUL FOR

Students studying multivariable calculus, particularly those preparing for exams involving vector functions and initial value problems. This discussion is also beneficial for educators and tutors assisting students in understanding these concepts.

mmont012
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Homework Statement


This is a solution to a problem that was on a quiz, and I am confused about how to do it. Especially lines
two (<0,1,1>=v(0)=<C1, 1+C2, C3> --> C1=0, C2=0, C3=1 and
five (<1,0,0>=r(0)=<1+ K1, K2, K3> -->K1=0, K2=0, K3=0
How do you do these steps? Can someone walk me through this process?
upload_2015-12-9_20-42-35.png


I'm studying for my final, and I KNOW that this will be one there.

Thank you in advance!
 
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Since ##v(t) = \int -\cos t \hat i -\sin t \hat j dt, ## you get ##v(t) = -\sin t \hat i + \cos t \hat j + \vec C ##.
Note that C can be any constant vector.
Plug in t = 0 and compare with your v(0) term to solve for vector C.
##v(0) = -\sin 0 \hat i + \cos 0 \hat j + \vec C = 0 \hat i + 1 \hat j + \vec C = \hat j + \hat k ##
This gives you ##\vec C = \hat k ##. Put this back into your equation for v(t) and you get ##v(t) = -\sin t \hat i + \cos t \hat j + \hat k ##.
Next, you integrate velocity to get position.
##r(t) = \int -\sin t \hat i + \cos t \hat j + \hat k dt = \cos t \hat i + \sin t \hat j + t \hat k + \vec K. ##
Where, again, vector K is any constant vector.
As before, put in t = 0 and compare with initial position ## \hat i ## to solve for the constant vector K.
##r(0) = \hat i = \cos 0 \hat i + \sin 0 \hat j + 0 \hat k + \vec K =1 \hat i + 0 \hat j + 0 \hat k + \vec K . ##
This shows you that vector K is the zero vector, so you can write r(t) as
##r(t) = \cos t \hat i + \sin t \hat j + t \hat k . ##
 
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