I've done 95% of this. I just don't get one specific part. General cal physics

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SUMMARY

The discussion revolves around a physics problem involving a fish's motion in a horizontal plane, characterized by its initial velocity vector (vi = 4.00i + 1.00j) m/s and a position vector relative to a rock (ri = 10i - 4.00j) m. After 20 seconds of constant acceleration, the fish's final velocity is given as (v = 20.0i - 5.00j) m/s. The main question is to determine the fish's position at 25 seconds, emphasizing the importance of incorporating the rock's position into the calculations. The participant expresses confusion over the necessity of the rock's position in the final calculation, despite successfully solving earlier components without it.

PREREQUISITES
  • Understanding of vector components in physics
  • Knowledge of kinematic equations, specifically Δd = vit + 1/2at²
  • Familiarity with constant acceleration motion
  • Ability to interpret position vectors in relation to reference points
NEXT STEPS
  • Review vector addition and its application in physics problems
  • Study the implications of reference points in motion problems
  • Learn how to apply kinematic equations to solve for final positions
  • Practice similar physics problems involving multiple vectors and reference points
USEFUL FOR

Students studying physics, particularly those focusing on kinematics and vector analysis, as well as educators looking for examples of common student misconceptions in motion problems.

randoreds
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Homework Statement


A fish is swimming in a horizontal place has velocity of ( vi = 4.00i + 1.00j) ms at a point in the ocean where the position relative to a certain rock is ri=(10.i- 4.00j)m. After the fish swims with constant acceleration for 20 s, it velocity is v = 20.0i -5.00j. Question C) what is the position at 25 s, if at a constant velocity.

Homework Equations


Δd= vit+ 1/2at^2

The Attempt at a Solution

Ok part a) so the components of V are .79 in the X direction and -0.3 in the Y direction. part b) was you had to find the direction of the vector with respect to the x-axis it is 339degree sign. But for part C, I'm solving for Xf and Yf.
Xf = (4.00) (25) + (1/2) (.79)(25)^2 (-- This is wrong. I checked the solution in the back. and the only difference is 10. I think it has to do with the rock. for some reason they randomly added the position of the Rock. So my question is why? Because when I was solving for the components(part A), I didn't need to add the position of the rock. And I got the right answer! Any help would be appreciated
 
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And my question is more, how would you know to do this? (if I encounter this doing other problems)
 
randoreds said:

Homework Statement


A fish is swimming in a horizontal place has velocity of ( vi = 4.00i + 1.00j) ms at a point in the ocean where the position relative to a certain rock is ri=(10.i- 4.00j)m. After the fish swims with constant acceleration for 20 s, it velocity is v = 20.0i -5.00j. Question C) what is the position at 25 s, if at a constant velocity.

Homework Equations


Δd= vit+ 1/2at^2

The Attempt at a Solution

Ok part a) so the components of V are .79 in the X direction and -0.3 in the Y direction. part b) was you had to find the direction of the vector with respect to the x-axis it is 339degree sign. But for part C, I'm solving for Xf and Yf.
Xf = (4.00) (25) + (1/2) (.79)(25)^2 (-- This is wrong. I checked the solution in the back. and the only difference is 10. I think it has to do with the rock. for some reason they randomly added the position of the Rock. So my question is why? Because when I was solving for the components(part A), I didn't need to add the position of the rock. And I got the right answer! Any help would be appreciated

More likely you will need to use just vectors for the equation to determine the answer. Don't find the diagonal components yet!
 

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