CBSEJEEClass 11

What is the work-energy theorem?

Answer

The work-energy theorem states that the net work done on a body equals the change in its kinetic energy, W = ΔKE = ½mv² − ½mu².

The working

Statement

The total work done by all forces acting on a body is equal to the change in the kinetic energy of that body.

Formula

W(net) = KE(final) − KE(initial) = ½mv² − ½mu², where u and v are the initial and final speeds.

Interpretation

Positive net work increases the body's speed, while negative net work (like friction) decreases it.

Usefulness

It lets us find speed or work without dealing with time or acceleration directly, which is handy when forces vary.

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