Conservation of Energy
Part of the Mechanics section of Coddy's Physics journey. Lesson 51 of 94.
When only gravity does work, the mechanical energy, KE + PE, stays the same:
½ m v0² + m g h0 = ½ m v² + m g h
The car starts at rest at A; the track has no friction.
Going down, PE turns into KE; going up, KE turns back into PE. The total is the same at every point, and the mass cancels.
Energy bars for a 100 kg car: the total is 9800 J at every point.
Challenge
A skateboarder rolls at 7 m/s at the bottom of a smooth ramp and coasts up it until she stops. Find the height h she reaches.
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