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Learning Goal

Part of: Work, Energy, and Simple Machines — 1 of 3 chapter items

Work, Power, and the Work-Energy Theorem

9.1

"In physics, the term **work** has a very specific definition. Work is application of force, $\mathbf{f}$, to move an object over a distance, *d*, in the direction that the force is applied." "When work done on an object increases only its kinetic energy, then the net work equals the change in the value of the quantity $\frac{1}{2} m \mathbf{v}^2$. This is a statement of the **work–energy theorem** ... $$W = \Delta KE = \frac{1}{2} m \mathbf{v}_2^2 - \frac{1}{2} m \mathbf{v}_1^2.$$" "**Power** is the rate at which work is done. In this case, rate means *per unit of time*. Power is calculated by dividing the work done by the time it took to do the work."

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"In physics, the term work has a very specific definition. Work is application of force, $\mathbf{f}$, to move an object over a distance, d, in the direction that the force is applied."
"When work done on an object increases only its kinetic energy, then the net work equals the change in the value of the quantity $\frac{1}{2} m \mathbf{v}^2$. This is a statement of the work–energy theorem ... $$W = \Delta KE = \frac{1}{2} m \mathbf{v}_2^2 - \frac{1}{2} m \mathbf{v}_1^2.$$"
"Power is the rate at which work is done. In this case, rate means per unit of time. Power is calculated by dividing the work done by the time it took to do the work."

What you'll learn

  1. State the scientific definition of work and calculate work using W = Fd
  2. Explain why some effortful activities (holding an object, carrying it at constant speed) do no work in the physics sense
  3. Describe kinetic and potential energy as the two forms of mechanical energy and relate work to changes in energy
  4. State and apply the work-energy theorem, W = ΔKE = ½mv₂² − ½mv₁²
  5. Explain the joule as the shared unit of work and energy and verify its equivalence to kg¡m²/s²
  6. Define power as the rate of doing work and calculate it using P = W/t

Slides

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Slides

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