Vector components - displacement

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Homework Help Overview

The problem involves calculating the average velocity of a train traveling in multiple directions over a specified time. The subject area pertains to vector components and displacement in physics.

Discussion Character

  • Exploratory, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants discuss calculating displacement using vector components and the need to find total x and y displacements. There are questions about using the Pythagorean theorem for resultant vectors and determining direction using arctangent.

Discussion Status

Some participants have provided guidance on calculating average velocity components and using the Pythagorean theorem. There is a lack of explicit consensus on the correctness of the final answer, as participants express uncertainty about the absence of provided solutions.

Contextual Notes

Participants note the absence of answer keys for verification, which contributes to their uncertainty regarding the correctness of their calculations.

shawli
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Homework Statement



A train moving at a constant speed of 100km/h travels east for 40min, then 30o east of north for 20 min, and finally west for 30min. What is the train's average velocity for the trip?

Homework Equations


The Attempt at a Solution



I think I have to calculate displacement from the given velocities, using vector components for 100km/h [30o E of N]. Then I find the total x displacement and total y displacement and divide by time (1.5h) to find the x and y velocities. I'm not sure what to do after this :S.
 
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shawli said:
Then I find the total x displacement and total y displacement and divide by time (1.5h) to find the x and y velocities.
That will give you the components of the average velocity. Find the magnitude of that vector.
 
Oh , I have to use Pythagorean theorem to find the resultant vector, right?

I divide that value by 1.5hr.

And finally I can find the direction by using the arctangent of the displacement components?

I end up getting 29.4 km/h [41 degrees north of east] , but I'm not sure if it's correct since I haven't been given answers to the problem.
 
shawli said:
Oh , I have to use Pythagorean theorem to find the resultant vector, right?

I divide that value by 1.5hr.

And finally I can find the direction by using the arctangent of the displacement components?
That's right.

I end up getting 29.4 km/h [41 degrees north of east] , but I'm not sure if it's correct since I haven't been given answers to the problem.
Looks good to me!
 
Last edited:
Thanks a ton!
 

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