Force Composer — Superposition of Forces on a Body

Active Forces

Gravity 9.8 m/s²

Spring stiffness k 14 N/m

Drag / damping c 0.8 kg/s

Thrust F_x 6.0 N

Live Readouts

|F_net|

0.0 N

|a|

0.0 m/s²

Speed |v|

0.0 m/s

How it works

Every force acting on the orange body is computed independently, then summed as vectors — the principle of superposition of forces — before Newton's second law converts the sum into motion:

F_gravity = (0, -m·g, 0)
F_spring  = -k · (x - x_anchor)      (Hooke's law)
F_drag    = -c · v                    (viscous damping, opposes velocity)
F_thrust  = (F_x, 0, 0)                (constant applied push)

F_net = F_gravity + F_spring + F_drag + F_thrust
a = F_net / m
v += a · dt   →   x += v · dt   (semi-implicit Euler)

Toggle checkboxes — switch individual force types on/off to isolate their effect; colored arrows on the body show each active force, the thick white arrow shows the net force.
Sliders — change gravity strength, the spring's stiffness k (anchored at the fixed ring), the drag coefficient c, and a constant horizontal thrust.
Release / Nudge — gives the body a small random kick so you can see the spring-drag system settle, oscillate, or run away depending on your settings.
The body is confined to a box; hitting a wall reflects its velocity with a restitution of 0.55 so the scene never runs off-screen.

This is exactly the workflow behind any physics-engine "object builder": define a body's mass and position, attach one or more force models to it, and let F = ma integrate the trajectory step by step.

Gravity Spring Drag Thrust Net force

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