Work
Part of the Mechanics section of Coddy's Physics journey. Lesson 47 of 94.
A force does work on an object when the object moves while the force acts. Only the part of the force along the motion counts:
W = F d cos θ
θ is the angle between the force and the displacement. Work is in joules.
Only the part of F along the displacement d does work.
A force perpendicular to the motion does no work: cos 90° = 0.
A force against the motion, like friction, does negative work: cos 180° = -1.
Challenge
A child pulls a wagon by its handle with 30 N at 60° above the ground, and the pull does 300 J of work. How far does the wagon move? Call the distance d.
Try it yourself
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
All lessons in Mechanics
1Vectors and Newton's Laws
Right TrianglesWhat is a Vector?Adding VectorsAxes and DirectionsVector ComponentsForces Around UsFriction and TensionNewton's First LawNewton's Second LawNewton's Third LawRecap - Net Force2Friction
What is Friction?Static FrictionKinetic FrictionFriction and Newton's LawsRecap - Sliding Crate3Inclined Planes
Forces on an InclineGravity ComponentsFrictionless InclineIncline with FrictionWill It Slide?Recap - Ramp Challenge6Projectile Motion
Independent AxesHorizontal LaunchLaunch at an AngleRange and Max HeightRecap - Hit the Target9Work and Energy
WorkKinetic EnergyWork-Energy TheoremGravitational PEConservation of EnergyPowerRecap - Roller Coaster12Impulse and Momentum
MomentumImpulseConservation of MomentumElastic CollisionsInelastic CollisionsRecap - Air Track15Simple Harmonic Motion
What is SHM?Mass on a SpringThe PendulumSHM GraphsEnergy in SHMRecap - Oscillator