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Work-Energy Theorem argues the net work done on a particle equals the change in the particle’s kinetic energy. According to this theorem, when an object slows down, its final kinetic energy is …
- 7.2: Kinetic Energy and the Work-Energy Theorem
Net work is defined to be the sum of work done by all...
- 7.2: Kinetic Energy and the Work-Energy Theorem
The Work-Energy Theorem. The principle of work and kinetic energy (also known as the work-energy theorem) states that the work done by the sum of all forces acting on a particle equals the change in the kinetic energy of the particle.
The work-energy theorem states that the net work done by the forces on an object equals the change in its kinetic energy. Learn more. For deeper explanations of the work-energy theorem, see our video work and the work-energy principle.
When we drop the rock the force of gravity causes the rock to fall, giving the rock kinetic energy. When work done on an object increases only its kinetic energy, then the net work equals the change in the value of the quantity 1 2 m v 2 1 2 m v 2. This is a statement of the work–energy theorem, which is expressed mathematically as
Net work is defined to be the sum of work done by all external forces—that is, net work is the work done by the net external force \(F_{net}\). In equation form, this is \(W_{net} = F_{net}d \, cos \, \theta\), where \(\theta\) is the angle between the force vector and the displacement vector.
The net work done by external forces on an object or system is equal to the change in total energy of that system: \begin{equation*} W_{net,external} = \Delta E \end{equation*} In fact, it is used throughout essentially all of science.
According to this theorem, when an object slows down, its final kinetic energy is less than its initial kinetic energy, the change in its kinetic energy is negative, and so is the net work done on it.
