How Do You Calculate the Rate of Change in Distance for a Ship's Journey?

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Discussion Overview

The discussion revolves around a related rates problem involving a ship's journey, specifically calculating the rate of change in distance between the ship and its starting location after a specified time. Participants explore the geometry of the situation and the application of trigonometric principles.

Discussion Character

  • Exploratory
  • Mathematical reasoning
  • Homework-related

Main Points Raised

  • One participant describes the ship's initial journey north at 18 km/h for 2 hours and then changing direction to 30 degrees north of east.
  • Another participant suggests drawing a triangle to visualize the problem and labels the axes accordingly.
  • There is a discussion about the interpretation of the 30 degrees north of east direction and how to represent it on a coordinate system.
  • A participant proposes a method to calculate the distances AB and BC based on the ship's journey and seeks clarification on the next steps.
  • One participant presents a calculation for AC using the Pythagorean theorem but expresses uncertainty about its correctness.
  • Another participant requests feedback on their method of solving the problem and seeks validation of their approach.

Areas of Agreement / Disagreement

Participants express uncertainty about the correctness of their calculations and methods. There is no consensus on the solution or the approach taken, as some participants are still clarifying their understanding of the problem.

Contextual Notes

Participants have not fully resolved the mathematical steps involved in calculating the rate of change in distance, and there are dependencies on how the positions of the ship are interpreted in relation to the coordinate system.

wolfsprint
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Ship started its journey from a Location A with velocity 18km/h to the north . after 2 hours the ship sailed in the direction 30 north of east find the rate of change in the distance between the location A and the position of the ship after 4 hours from the start.

i have no idea how to solve this problem and would really like how to?
 
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Re: Related time rate , ship problem

wolfsprint said:
Ship started its journey from a Location A with velocity 18km/h to the north . after 2 hours the ship sailed in the direction 30 north of east find the rate of change in the distance between the location A and the position of the ship after 4 hours from the start.

i have no idea how to solve this problem and would really like how to?


You have a related rates problem. Have you drawn the triangle the problem forms? Have you labeled the triangle with what you know?

If not, that is step one. Then what are the equations related to a triangle we could use?
 
Re: Related time rate , ship problem

I understand i have to draw the x-axis and the y-axis and plot and join the dots to form a triangle but the problem is I am having trouble understanding the positions of the ships
 
Re: Related time rate , ship problem

wolfsprint said:
I understand i have to draw the x-axis and the y-axis and plot and join the dots to form a triangle but the problem is I am having trouble understanding the positions of the ships

The 30 degrees north of east part?

If we let the east-west axis be our x-axis, then 30 degrees north of east is $\frac{\pi}{6}$.
 
Re: Related time rate , ship problem

so A is the origin and when the ship sails north i put a dot a bit further up and for the 30 north of east i draw an imaginary x-axis on the dot on the north direction and put a point in the 30 degrees direction? what's next?
 
Re: Related time rate , ship problem

wolfsprint said:
so A is the origin and when the ship sails north i put a dot a bit further up and for the 30 north of east i draw an imaginary x-axis on the dot on the north direction and put a point in the 30 degrees direction? what's next?

That is what I would do, let A be the origin. Then the ship sailed 2 hours at 18km/h so the from A to B we have 36km.
Then the ship sailed at 30 degrees from point b for 2 hours to point C. What you want to find is the rate of change of the AC
 
Re: Related time rate , ship problem

ok so this is how i solved the problem :
After t hours i presumed the following
AB = 36+2t
BC = 36+2t
we need to find AC so
AC^2 = (36+2t)^2 + (36+2t)^2
AC = 12(Root)26
is this correct?
 
Re: Related time rate , ship problem

Thanks for understanding , and i would like to know if my method of solving is correct please?
 
Re: Related time rate , ship problem

wolfsprint said:
Thanks for understanding , and i would like to know if my method of solving is correct please?

Look at the this example page 192
 

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