Questions regarding generalized work equation

  • Context: Undergrad 
  • Thread starter Thread starter Obliv
  • Start date Start date
  • Tags Tags
    generalized Work
Click For Summary
SUMMARY

The discussion centers on the generalized work equation, specifically the integral form W = ∫ F · ds, which applies to both conservative and non-conservative forces. The participant clarifies that the work done by conservative forces is equal to -ΔPE, and provides an example using Hooke's Law for springs, yielding W = -1/2(kx²) when the spring stretches. The conversation also addresses the dimensionality of the integral, confirming that bounds can be established in three dimensions, and emphasizes that work is a change agent for energy rather than energy itself.

PREREQUISITES
  • Understanding of calculus, particularly line integrals
  • Familiarity with concepts of work and energy in physics
  • Knowledge of conservative and non-conservative forces
  • Basic principles of multivariable calculus
NEXT STEPS
  • Study multivariable calculus to understand line integrals in depth
  • Explore the relationship between work and potential energy (PE) in conservative systems
  • Investigate the implications of non-conservative work on energy transformations
  • Learn about Hooke's Law and its applications in mechanical systems
USEFUL FOR

Students of physics, educators teaching mechanics, and anyone interested in the mathematical foundations of work and energy concepts.

Obliv
Messages
52
Reaction score
1
Hello, I am trying to generalize the work equation and understand the very definition of it. From what I understand, Work is the energy required to displace an object with a force in the direction of the displacement. (also the change in kinetic energy but I'm not going to worry about that yet)
W = \int \vec{F} \cdot {d}\vec{x} This equation makes sense to me. If I were to add bounds to the integral, would they be in 3-D if the displacement and force is in 3-D?
Otherwise
W = \int_{x_i}^{x_f} {F_x} {dx} + \int_{y_i}^{y_f} {F_y} {dy} + \int_{z_i}^{z_f} {F_z} {dz}
This method would get the work with calculus I know of. Is it possible to make bounds in multiple dimensions? If so, how would one solve them? Thank you!

edit: Oh one more question: This equation describes non-conservative work, right? What would describe conservative work? Just this? W = \vec{F} \cdot \vec {d}
 
Last edited:
Physics news on Phys.org
It describes a force that varies with position, unlike your second formula.

The generalized work integral is a line integral, which you'll be able to solve in the general case after you've taken multvariable calculus. It essentially let's you integrate over whatever path you need to integrate over for the problem.
 
The generalized equation for
Work = \int F.ds applies to both conservative and non conservative forces. For conservative forces , the work done is equal to - \Delta PE . For work done by conservative forces like springs in particular, performing the work integral where F = -kx yields W = -1/2(kx^2) when the spring stretches from rest to x. This is the negative of the change in its PE. Work is not energy, it causes a change in energy, which might be positive or negative or zero. Net work is change in KE, while non conservative work is change in PE plus change in KE. You can also regard non conservative work as the negative of the change in thermal/other energy.
 

Similar threads

  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 31 ·
2
Replies
31
Views
4K