Understanding the Net Work Energy Concept: Defining F in Work Equations"

[caljuice]

I've been confused about work. I know it equals F x D. But what is F? Is it the netforce or the force being exerted.

If you are pushing up an object up an incline with 200N and the opposing force of gravity + friction is 100N for D=20m. Is Work, Fnet x D or 200N x D?

Does the same apply to the Worknet in this equation --> delta = $

Worknet=$ke + $pe + Wf


If I wanted to find $ke and had wf and pe and the components of work. Would I use Fnet or force that's moving the object.

I always thought it was Fnet but some questions have been confusing me. Thanks

 

[tiny-tim]

Hi caljuice!

You only need to know the work done so that you can use the work-energy theorem …

so you have to include all the forces (that do work) … gravity, friction, pushing forces, everything.

(The normal force, of course, does no work)

If the body isn't rotating (so all its parts have the same velocity), then you can either multiply the net force by distance, to get "net work", or you can calcualte the work done by each force separately.

 

[astrokreng]

F in work equations represents the force that is being applied to an object. This can be the net force, which takes into account all the forces acting on the object, or it can be a specific force that is being exerted. In your example of pushing an object up an incline, F would be the net force of 200N, as this is the force that is overcoming the opposing forces of gravity and friction.

In the equation Worknet = $ke + $pe + Wf, Fnet is the net force that is being applied to the object. The other components, $ke (kinetic energy), $pe (potential energy), and Wf (work done by external forces), all contribute to the overall net work being done on the object.

If you wanted to find $ke using the components of work, you would still use the net force (Fnet) as this is the force that is causing the change in kinetic energy. It is important to always use the correct force in work equations to ensure accurate calculations.

It is understandable to be confused about work and the different forces involved, but it is important to remember that F in work equations represents the force that is being applied to an object. Whether it is the net force or a specific force, it is crucial to use the correct value to accurately calculate work.