⚛ Physics LabWork and Energy · v0.25 beta

DYNAMICS · WORK–ENERGY THEOREM

Work and Energy

Explore how gravity converts potential energy into kinetic energy and howfriction and inelastic collisions dissipate mechanical energy. Calculate work done by each force and check the energy balance at any time.

Physical Parameters

kg
°
m
m/s²
dimensionless
dimensionless
N
m/s
m
s

Sign Convention: s increases from the bottom to the top of the slope. Potential energy is zero at the bottom (U = 0 J). Work is positive when a force assists displacement and negative when it opposes displacement.

Simulation and Energy Balance

True-Scale Geometry 1:1: horizontal and vertical metres use the same scale. The incline and the motion use the same coordinate transform.

Energy and Work at Selected Time

Kinetic KPotential UMechanical Energy EDissipation Q

Position s—
Velocity v—
Kinetic Energy K—
Potential Energy U—
Mechanical Energy E—
Balance ΔE − Wₙ꜀—

During frictionless motion with no external work, E = K + U is conserved. At an end stop the body undergoes a perfectly inelastic impact with permanent stopping, which dissipates energy: the mechanical system is not conservative.

Work Done by Each Force and Dissipation

Work by Gravity Wg—
Work by Applied Force Wa—
Work by Friction Wf—
Work by Impacts Wu—
Total Work Wtot—
Change in K—
Dissipated Energy Q—
Distance Travelled—

Synchronized Energy and Motion Graphs

Click a graph or enter an exact time. Impact discontinuities are highlighted; they do not represent a continuous change in energy.

Selected time: 0.00 sThe selected time updates the graphs, readouts, scene and calculations.

Kinetic Energy K(t) and Potential Energy U(t)

Mechanical Energy E(t) and Energy Balance

Accumulated Work of Forces (J)

Position s(t)

Velocity v(t)

Values Table

t (s)s (m)v (m/s)K (J)U (J)E (J)W gravity (J)W external (J)W friction (J)W impacts (J)Residual (J)Regime

SI units, comma-separated, decimal point.

Model Assumptions

The body is treated as a point particle on a rigid incline of length L, constant angle θ, with uniform gravity. The normal component of weight is balanced by the surface. The normal force does no work because it is perpendicular to displacement.

The forces acting along the incline are constant: gravity, an external force parallel to the plane, and Coulomb static and kinetic friction. Static friction can maintain rest without doing work; kinetic friction always does negative work during sliding.

The energy graphs accumulate work along the actual distance travelled, including after a reversal. The impact balance accounts for instantaneous kinetic energy loss; the body locks at the boundary without bouncing.

Air drag, rotational motion, deformation and explicit heating are excluded. Lost mechanical energy is recorded as dissipation; it does not disappear from the total energy of the environment.

FROM FORCES TO ENERGY BALANCE

Step-by-Step Calculations

General equations, dimensional substitutions, intermediate steps and results in joules.

Calculations retain full internal precision; only displayed results are rounded. Each equation appears on its own line, with MathML fallback.

by Andrea Minini