Finding Net Force [w/ Vector Addition]

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Homework Help Overview

The problem involves calculating the net force acting on a 20 kg object subjected to multiple forces, specifically a 90 N force at an angle, a 40 N force directed south, and another 40 N force at a different angle. The objective is to find the net force and the resulting acceleration.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the addition of vector components to determine the resultant force. Questions arise regarding the use of the Pythagorean theorem for finding the resultant vector's magnitude and direction. There is also inquiry about the necessity of including direction in the final answer.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of how to calculate the resultant force and its implications for acceleration. Some guidance has been provided regarding the relationship between net force and acceleration direction.

Contextual Notes

There are indications of uncertainty regarding the application of vector addition and the significance of direction in the final results. Participants are also navigating the constraints of the homework problem without definitive conclusions.

harujina
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Homework Statement



A 20 kg object is being acted on by a 90 N [E60N] force, a 40 N force, and a 40 N [E27S] force.
Find the net force acting on the object and its acceleration.

Homework Equations



ƩF = ma

The Attempt at a Solution



I understand that I have to add vector components here.
So as a result, I got 80.64 N [E] and 19.78 N [N].
I got a force pulling North and a force pushing East. But now I don't know what to do with these forces...?
 
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Assuming you worked correctly so far, these are the components of the resultant force.
You need to find the magnitude and the direction (angle) of this resultant.
 
harujina said:

Homework Statement



A 20 kg object is being acted on by a 90 N [E60N] force, a 40 N force, and a 40 N [E27S] force.
Find the net force acting on the object and its acceleration.

Homework Equations



ƩF = ma

The Attempt at a Solution



I understand that I have to add vector components here.
So as a result, I got 80.64 N [E] and 19.78 N [N].
I got a force pulling North and a force pushing East. But now I don't know what to do with these forces...?


Well, what force vector did you get when you added the components of the original three vectors which were given? Don't you get a Resultant vector with a magnitude and a direction?

Can't you use this resultant vector to answer the second part of your problem?
 
Oh, so is it right for me to use Pythagorean theorem here to find the resultant vector?
and then that would be the net force which can be used to determine acceleration, correct?

*I worked it out and got 83.03 N [E3.5N]
Just wondering if it's necessary to include direction [E3.5N]
I know acceleration is a vector quantity but what does this implicate? Simply the direction of acceleration for my final answer?
 
harujina said:
Oh, so is it right for me to use Pythagorean theorem here to find the resultant vector?
and then that would be the net force which can be used to determine acceleration, correct?

*I worked it out and got 83.03 N [E3.5N]
Just wondering if it's necessary to include direction [E3.5N]
I know acceleration is a vector quantity but what does this implicate? Simply the direction of acceleration for my final answer?
Yes, the direction of the acceleration is always in the direction of the net force.
 
PhanthomJay said:
Yes, the direction of the acceleration is always in the direction of the net force.

Ok, thank you!
 

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