Calculating the Magnitude of a Force

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Homework Help Overview

The problem involves calculating the magnitude of a third force acting on a particle that moves with a constant velocity, given two other forces. The context is within the subject area of dynamics and force analysis.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the implications of constant velocity on acceleration and the net force. There are attempts to set up equations based on the components of the forces to find the third force. Questions arise regarding the relationship between net force and velocity, as well as how to properly set the equations equal to zero.

Discussion Status

The discussion is ongoing with participants exploring different interpretations of how to relate the forces to the constant velocity condition. Some guidance has been provided regarding setting the net force to zero, but there is still uncertainty about the application of this concept to the problem.

Contextual Notes

Participants are navigating the implications of the constant velocity condition, which leads to a zero net force, and are trying to clarify how to apply this to the components of the forces involved.

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Homework Statement



Three forces act on a particle that moves with a constant velocity v = 2 m/s x – 7 m/s y . Two of the forces acting on this particle are F1 = -10.0N x + 9.0N y + 4.0N z and F2 = = -1.0N x + 4.0N y + 2.0N z . What is the magnitude of the third force?


Homework Equations



Fnet=ma?

The Attempt at a Solution



I'm actually not even sure what the question is asking to be honest...
 
Last edited:
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F=ma, indeed. So a=0 since it's moving with constant velocity, so the sum of the forces is zero. What's the third force? Once you have it, figure out it's magnitude.
 
So I just go:

Fx: -10-1+____=2
Fy: 9+4+___=-7
Fz: 4+2+__=0
Where the blanks are the third force?
 
No. The velocity is CONSTANT. So the acceleration is ZERO. Set all of your equations equal to zero.
 
All of which equations? I get that Fnet = 0 because there is no acceleration, but how do I relate that to velocity? or to the components of the other forces?
 
Lorelyn said:
So I just go:

Fx: -10-1+____=2
Fy: 9+4+___=-7
Fz: 4+2+__=0
Where the blanks are the third force?

All of THESE equations. The velocity doesn't matter since it's constant. The equations above give you the components of Fnet. Which should be zero, so replace the 2 and -7 with 0. Now figure out what goes in the blanks to give you the third force.
 

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