Finding Work from Force Equation

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mintsnapple
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Homework Statement


Textbook problem 11P26: a force F = Ce^(ax) acts on an object at position x, where C and a are constants. Asks for the work done by F as the object moves (a) from x = 0 to x = 2a^-1, (b) from x = 2a^-1 to x = 4a^-1, (c) from x = 4a^-1 to 0.



Homework Equations


W = F*d


The Attempt at a Solution


a. W = Ce^(ax)*2a^-1
b. W = Ce^(ax)*2a^-1
c. w = Ce^(ax)*(-4a^-1)

I feel like this problem is more than just this simple...
 
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mintsnapple said:

Homework Statement


Printed textbook problem 11P26: force F = Ce^(ax) acts on an object at position x, where C and a are constants; asks for work done from x = 0 to 2a^-1, from 2a^-1 to 4a^-1, and from 4a^-1 to 0.


Homework Equations


W = F*d

The Attempt at a Solution


a. W = Ce^(ax)*2a^-1
b. W = Ce^(ax)*2a^-1
c. w = Ce^(ax)*(-4a^-1)

I feel like this problem is more than just this simple...
Those results don't look right.

What do you get for the indefinite integral ## \displaystyle \int C e^{\alpha x}\ dx \ \ ? ##
 
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SammyS said:
Those results don't look right.
... in particular, there should not be any x in the answers.
 
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Ah, I just re-read the question and saw my mistake.

How would I approach this problem with a changing force though? Do I just plug in the end position, and multiply that force by displacement?
 
mintsnapple said:
Ah, I just re-read the question and saw my mistake.

How would I approach this problem with a changing force though? Do I just plug in the end position, and multiply that force by displacement?
dW = F dx .

You need to integrate to integrate the force with respect to x .
 
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SammyS said:
dW = F dx .

You need to integrate to integrate the force with respect to x .

Ahh, I see. So integrate the force with respect to x, and use the positions as my limits.
 
mintsnapple said:
Ahh, I see. So integrate the force with respect to x, and use the positions as my limits.

Yes.