Calculating New Acceleration with F=ma: A Homework Problem

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Homework Help Overview

The discussion revolves around calculating the new acceleration of an object when its force and mass are altered. The original acceleration is given as 2.00 m/s², and the problem involves applying the equation F=ma to find the new acceleration after dividing the force by 3 and the mass by 7.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the application of the equation F=ma and question the steps taken to derive the new acceleration. There is confusion regarding the use of the original acceleration in the calculations and the interpretation of the modified force and mass.

Discussion Status

Participants are actively engaging with each other's reasoning, with some clarifying the setup of the problem and others questioning the calculations. There is an ongoing exploration of the correct approach to find the new acceleration, but no consensus has been reached on the final value.

Contextual Notes

Some participants express uncertainty about the interpretation of the original acceleration and how it should be applied in the context of the modified force and mass. There is a lack of clarity on the steps leading to the new acceleration calculation.

juju1

Homework Statement


If the acceleration of an object is 2.00 m/s2 and the force on it is divided by 3 and its mass is divided by 7, what is the new acceleration?

Homework Equations

The Attempt at a Solution


so I know the equation we use is F=ma, and so i did (F/3)=(m/7) 2a
i divided by (m/7) on both sides to get (7/3)(F/m)=2a
then i divided by 2 on both sides to get 1.17 m/s/s = a
but it is showing that I am wrong, where did I go wrong?[/B]
 
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juju1 said:
so I know the equation we use is F=ma, and so i did (F/3)=(m/7) 2a
I don't see how you got this last equation, especially the 2a on the right side.
 
Newton's equation is F=ma
so i substituted the givens into that
 
Okay, the new force is F/3, where F is the original force. And m/7 is the new mass, where m is the original mass.

Why did you write 2a for the acceleration?
 
because the acceleration is 2?
 
juju1 said:
because the acceleration is 2?
That's the original acceleration.

Originally, you have Fold = moldaold, where the subscripts indicates the old (original) values.

After the changes, you would have Fnew = mnewanew. You need to solve for anew.
 
oh okay...so solving for a new then, i got 2.33 m/s/s
 
juju1 said:
oh okay...so solving for a new then, i got 2.33 m/s/s
I don't think that's right. Can you show your steps to see how you got 2.33 m/s2?
 
OH WAiiitttt i believe i got it now. I was dividing by 2 not multiplying, so i got 4.67 m/s/s!
 
  • #10
Yes, that's the right answer. I hope it makes sense.
 
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