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uestions
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When does the Kinetic Work Energy Theorem not apply to a situation? Or better, is there a general form of the equation where work can equal the change in any energy? What is work besides a force and a distance?
uestions said:When does the Kinetic Work Energy Theorem not apply to a situation?
uestions said:is there a general form of the equation where work can equal the change in any energy?
uestions said:What is work besides a force and a distance?
Here's something that I wrote in another thread that may clarify how the "work"-energy theorem, when thought of as an application of Newton's 2nd law, may be applied to deformable bodies.TysonM8 said:The Work-Energy Theorem only applies to rigid bodies. That is, if the work is not used to deform the object.
Doc Al said:The so-called 'work'-Energy theorem is really an application of Newton's 2nd law, not a statement about work in general. Only in the special case of a point mass (or rigid body) is that "work" term really a work (in the conservation of energy sense).
If you take a net force acting on an object (like friction) and multiply it by the displacement of the object's center of mass, you get a quantity that looks like a work term but is better called pseudowork (or "center of mass" work)--what it determines is not the real work done on the object, but the change in the KE of the center of mass of the object. This is usually called the "Work-Energy" theorem:
[tex]F_{net}\Delta x_{cm}=\Delta (\frac{1}{2}m v_{cm}^2)[/tex]
Despite the name, this is really a consequence of Newton's 2nd law, not a statement of energy conservation.
If the velocity doesn't change, the work-kinetic energy theorem just says that the net work must be zero. You do work when you lift an object at constant speed, but gravity is also doing negative work.uestions said:How can work be done to an object that has a change in potential energy, but no change in velocity?
The Kinetic Work Energy Theorem states that the net work done on an object is equal to the change in its kinetic energy. In other words, the work done on an object is equal to the amount of energy it gains or loses in motion.
The equation for the Kinetic Work Energy Theorem is W = ΔKE = KEf - KEi, where W represents the work done on the object, ΔKE is the change in kinetic energy, and KEf and KEi represent the final and initial kinetic energies, respectively.
The Kinetic Work Energy Theorem is a specific application of the Law of Conservation of Energy, which states that energy cannot be created or destroyed, only transferred from one form to another. In this case, the work done on an object is equal to the change in its kinetic energy, which is a form of energy.
The Kinetic Work Energy Theorem can be seen in many everyday situations, such as a car accelerating on a road, a ball rolling down a hill, or a person swinging on a playground swing. In all of these examples, work is done on the object, resulting in a change in its kinetic energy.
The Kinetic Work Energy Theorem is an important concept in engineering and technology, as it allows for the calculation and prediction of the amount of work needed to move an object at a certain speed or distance. It is also used in the design and analysis of machines and structures, such as roller coasters and bridges, to ensure that they can withstand the forces and work involved in their operation.