Calculating Duck's Displacement in 2.52s with F=ma and Kinematics Equations

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Homework Help Overview

The discussion revolves around calculating the displacement of a duck subjected to two forces while paddling in water. The problem involves concepts from kinematics and Newton's second law (F=ma), focusing on the duck's mass, the forces acting on it, and its initial velocity.

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Approaches and Questions Raised

  • Participants explore the calculation of forces and acceleration, with one participant detailing their approach using F=ma and kinematics equations. Questions arise regarding the accuracy of displacement and angle calculations, with participants comparing their results and discussing potential discrepancies.

Discussion Status

Participants are actively engaging with each other's calculations, noting similarities and differences in their results. Some guidance is offered regarding the calculations, particularly concerning the final velocity and displacement. There is an ongoing exploration of the angle of displacement, with no clear consensus reached yet.

Contextual Notes

Participants express uncertainty about the accuracy of their angle calculations and the impact of their differing results on the overall problem. The original poster indicates that their answers were incorrect, prompting further discussion on the assumptions made during calculations.

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1.) A duck has a mass of 2.35 kg. As the duck paddles, a force of 0.144 N acts on it in a direction due east. In addition, the current of the water exerts a force of 0.202 N in a direction of 54.5° south of east. When these forces begin to act, the velocity of the duck is 0.130 m/s in a direction due east. Find the magnitude and direction (relative to due east) of the displacement that the duck undergoes in 2.52 s while the forces are acting.

2.) F=ma
Kinematics equations

3.) So, I worked out that the x-component of F2 is 0.117N and added that to 0.144N. I then plugged the answer (0.261N) into the F=ma formula and got a=0.11m/s^2. I then used the equation d=(Vi)t+1/2(a)(t^2) and got d=0.677m.
Then, I used the x-component of 0.261N and the Y-component of F2(the only y-component) and solved for the angle getting 31.5deg. I subtracted this from 360 to get the answer of 328.5deg relative to due east. My answers came out to be incorrect.
Please help!
 
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For the east direction, I agree with your force of .261 N and a = 0.111.
I used V = Vi + at to get the final velocity of .4099 and then used
d = Vavg *t = (.13+.4099)/2*2.52 = .6803 m East.
Very close to your .677 but could that be what is getting you the wrong answer?
 
Delphi51 said:
For the east direction, I agree with your force of .261 N and a = 0.111.
I used V = Vi + at to get the final velocity of .4099 and then used
d = Vavg *t = (.13+.4099)/2*2.52 = .6803 m East.
Very close to your .677 but could that be what is getting you the wrong answer?

Um, I think that it may be the direction that's getting me the wrong answer. What did you get for that?
 
Finished it now. We are way different on the angle. For the south distance I got about 0.2 m and an angle of less than 20 degrees south of east, which would be more than 340 degrees counterclockwise from east.
 

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