Work-energy theorem

Science

Definition

A principle stating that the net work done on an object equals the change in its kinetic energy. If positive net work is done, the object speeds up; if negative net work is done (such as by friction), the object slows down.

Examples

  • A car accelerating from rest — the engine does net positive work, increasing the car's kinetic energy
  • A baseball player catching a ball — the glove does negative work, reducing the ball's kinetic energy to zero
  • A roller coaster at the bottom of a hill has maximum kinetic energy equal to the work done by gravity during the descent
Key Fact

W_net = ΔKE = ½mv₂² − ½mv₁²

Related Terms

Work Kinetic energy Conservation of energy Net force

Study This Concept

Practice work-energy theorem with free review games in these units:

AP Physics 1 Unit 3: Work Energy and Power