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Home/Classical Mechanics/Spring-Mass System

Spring-Mass System

Simple harmonic motion with adjustable spring constant and damping.

Parameters

40 N/m
2 kg
0.15 N·s/m
80 px

Display

Shortcuts

  • •Space or Enter — start oscillation
  • •R — stop and clear graphs

Measured values

ω₀ = √(k/m)4.472rad/s
T (undamped)1.405s
T (underdamped)1.405s
x80.0
v0.0
KE0.0J
PE (½kx²)128000.0J

Live graphs

About this model

A mass attached to a horizontal spring sliding on a frictionless surface is a foundational model in classical mechanics. This simulator visualizes the resulting simple harmonic motion (SHM), governed by Hooke's Law and Newton's Second Law. The restoring force exerted by the spring is F = -kx, where k is the spring constant (stiffness) and x is the displacement from equilibrium. Applying Newton's Second Law (F = ma) yields the differential equation m(d²x/dt²) = -kx. The solution is sinusoidal motion: x(t) = A cos(ωt + φ), where A is the amplitude, φ is the phase constant, and the angular frequency ω = √(k/m) determines the period T = 2π/ω. The simulator introduces a velocity-dependent damping force, -bv, modeling friction or air resistance, leading to underdamped, critically damped, and overdamped regimes. Key simplifications include a massless spring, a point mass, a perfectly linear spring obeying Hooke's Law across all displacements, and a one-dimensional, frictionless surface for the undamped case. By interacting with parameters like k, m, b, and initial conditions, students directly explore the core principles of oscillatory dynamics, the relationship between force and acceleration, energy conversion between kinetic and potential forms, and how damping dissipates energy from the system.

Who it's for: High school and introductory college physics students studying oscillations, waves, and Newtonian mechanics.

Key terms

  • Simple Harmonic Motion
  • Hooke's Law
  • Damping
  • Spring Constant
  • Restoring Force
  • Angular Frequency
  • Oscillation Period
  • Newton's Second Law

How it works

A mass on a frictionless horizontal surface attached to an ideal spring obeys mẍ + cẋ + kx = 0. With light damping, oscillations decay; without driving, energy sloshes between kinetic and potential ½kx².

Key equations

mẍ + cẋ + kx = 0
ω₀ = √(k/m),   PE = ½kx²
Underdamped: ω_d = √(ω₀² − (c/2m)²), T = 2π/ω_d. Undamped motion uses velocity Verlet for better energy behaviour.

Frequently asked questions

Why does increasing the mass make the oscillation slower?
The oscillation period T is given by T = 2π√(m/k). This shows that period is proportional to the square root of the mass. A larger mass has more inertia, meaning it resists changes in motion more strongly. The spring force remains the same for a given displacement, so the larger mass accelerates less, leading to a longer time for each complete cycle.
What is the difference between 'angular frequency' (ω) and regular frequency (f)?
Angular frequency (ω, in radians per second) describes how fast the phase angle of the oscillation changes. Regular frequency (f, in Hertz or cycles per second) counts how many complete oscillations occur per second. They are directly related: ω = 2πf. In the spring-mass system, ω = √(k/m), while f = (1/(2π))√(k/m).
Does this model apply to a vertical spring-mass system?
Yes, but with a crucial note. Gravity shifts the equilibrium position downward, but relative to this new equilibrium point, the motion is identical to the horizontal case. The restoring force is still -k*x, where x is now measured from the stretched equilibrium position, not the spring's natural length. The period formula T = 2π√(m/k) remains unchanged.
What does 'critical damping' mean, and where is it useful?
Critical damping is the specific damping level where the system returns to equilibrium as quickly as possible without oscillating. It represents the boundary between underdamped (oscillatory) and overdamped (slow, non-oscillatory) return. This is highly desirable in real-world applications like car shock absorbers and door closers, where you want to eliminate bouncing and settle smoothly.