Newtonian mechanics
Work and power
Study the work of a constant force versus displacement and angle. Verify and power using the simulation readouts.
Equipment
- Model of a force pulling a body on a plane with a force vector
- Sliders for force F (0–100 N) and displacement s (0–10 m)
- Slider for the angle θ between force and displacement
- Time slider, Reset button, and readouts for W and P
Procedure
Measure work versus F and s
Set θ = 0° then vary F and s independently, reading work W on the display: work is proportional to both, giving when force is parallel to displacement. Press Reset between measurements.
Vary θ and watch cos θ
Hold F, s and increase θ from 0 to 180°: work falls as — zero at 90° (perpendicular force does no work) and negative beyond (resistive force). Compare each reading with .
Compute the average power
Keep F, s, θ fixed and change the time slider: the same W but higher P = W/Δt when done faster. From the readouts, predict the time needed for P to reach a chosen value, then check.
Simulation
Experiment history
The concept of mechanical "work" was defined by Gaspard-Gustave Coriolis in 1829 as force times displacement, in his study of machine efficiency; he also named kinetic energy. Power became a practical notion with James Watt, who marketed steam engines by comparison with "horsepower" (1782) — 1 hp ≈ 746 W today.
James Prescott Joule proved in the 1840s that mechanical work, heat, and electricity are forms of one conserved quantity — his famous paddle-wheel experiment measured the mechanical equivalent of heat. The units joule and watt commemorate these works.