Relating force, displacement, time and velocity

Click For Summary

Homework Help Overview

The problem involves a duck with a mass of 2.7 kg experiencing two forces while paddling in water. One force is 0.13 N due east, and the other is 0.20 N at an angle of 54° south of east. The task is to determine the displacement of the duck over a time period of 2.3 seconds while these forces are acting.

Discussion Character

  • Mixed

Approaches and Questions Raised

  • Participants discuss vector components of the forces acting on the duck and explore the resultant force. There are attempts to calculate acceleration and displacement using kinematic equations. Some participants express confusion regarding the direction of the vectors and the setup of the problem.

Discussion Status

The discussion includes various attempts to clarify the vector components and their directions. Some participants have provided suggestions for breaking down the forces into their components, while others are working through their calculations and expressing uncertainty about their results.

Contextual Notes

There is a noted confusion regarding the direction of the vectors, particularly in how they are represented in diagrams. Participants are also navigating the implications of their assumptions about positive and negative directions in their calculations.

Ohoneo
Messages
22
Reaction score
0

Homework Statement


A duck has a mass of 2.7 kg. As the duck paddles, a force of 0.13 N acts on it in a direction due east. In addition, the current of the water exerts a force of 0.20 N in a direction of 54° south of east. When these forces begin to act, the velocity of the duck is 0.13 m/s in a direction due east. Find the magnitude and direction (relative to due east) of the displacement that the duck undergoes in 2.3 s while the forces are acting.


Homework Equations


F = ma
v2-v02 = 2a(x-x0)
x = x0+v0t+1/2 at2
v = vat


The Attempt at a Solution



First, I drew a diagram. The .13 N is a vector going from right to left. Then, the .20 N vector connects and heads south east. Because it is 54 degrees south of east, that means the interior angle where the two vectors join is 126 degrees.
I then found the results.
I found the resultant vector to be .293 N.
I then used the F=ma equation to find acceleration which I found to be .1096 m/s2.
I then plugged this into v = v a t (v = .13 + .1096 (2.3)) to find that final velocity was .38 m/s.
I then plugged all of this into the equation v2-v02 = 2a(x-x0).
I substituted: .382-.172 = 2(.1096)x
I solved for x to be .589
I then used my diagram to find tan-1(.2/.13) to get 59 degrees as an answer.

Unfortunately, all of this was wrong.
 
Physics news on Phys.org
try splitting up the .2oN force in a direction of 54 degrees south of east into vectors, and use those numbers to solve the rest.
 
Sniperman724 said:
try splitting up the .2oN force in a direction of 54 degrees south of east into vectors, and use those numbers to solve the rest.

Oops, sorry. I should have clarified that I did that. That's how I got the resultant vector; I found the components of the vector that had a force of .20 N. The vector in the x direction was .12 N and the vector in the y direction was -.16 N.
 
Ohoneo said:
As the duck paddles, a force of 0.13 N acts on it in a direction due east.
...
First, I drew a diagram. The .13 N is a vector going from right to left.

Right to left is due west.
 
vertigo said:
Right to left is due west.

Okay, apparently I'm terrible at explaining myself. I drew it left to right. Regardless, I made east the positive direction and south is the negative direction.
 

Similar threads

  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 19 ·
Replies
19
Views
8K
Replies
3
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
Replies
10
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 8 ·
Replies
8
Views
1K
  • · Replies 21 ·
Replies
21
Views
3K
  • · Replies 7 ·
Replies
7
Views
3K
  • · Replies 12 ·
Replies
12
Views
3K