Physics Lab • Mechanics

Conservation of Linear Momentum

1D Collision Dynamics & Dynamic Energy Transformation Analysis

Interactive Collision Track

Collision Type:
Speed:
Preset Experiments:

Live Momentum & Energy Diagnostics

Before Collision (Initial)

p₁ = m₁ · u₁ +30.0 kg·m/s
p₂ = m₂ · u₂ -20.0 kg·m/s
Ptotal, initial +10.0 kg·m/s

After Collision (Final)

p₁' = m₁ · v₁ --
p₂' = m₂ · v₂ --
Ptotal, final --

Kinetic Energy Comparison (KE = ½ m v²)

Initial KE (Ki): 130.00 J
Final KE (Kf): 130.00 J
KE Loss (ΔK): 0.00 J (0.0%)

In Elastic collisions, kinetic energy is strictly conserved.

Visual Vector Momentum Comparison (Ptotal) Direction: ← Negative (−) | Positive (+) →
BEFORE
+10.0 kg·m/s
AFTER
+10.0 kg·m/s

Momentum Analytics Graph

Object 1 Momentum (p₁) Object 2 Momentum (p₂) Total Momentum (Ptotal)

Experimental Observation Data Table

Reading # Mode Collision m₁ (kg) m₂ (kg) u₁ (m/s) u₂ (m/s) v₁ (m/s) v₂ (m/s) Pinitial (kg·m/s) Pfinal (kg·m/s) ΔP (kg·m/s) KEinitial (J) KEfinal (J)
No readings recorded yet. Click "RECORD DATA" to save the current simulation state.

Working Principle & Physics Framework

1. Concept of Linear Momentum

Linear momentum (p) is defined as the product of an object's mass (m) and its velocity vector (v):

p = m · v

Momentum is a vector quantity possessing both magnitude and direction. In one-dimensional motion, direction is indicated by algebraic sign: rightward motion is positive (+), and leftward motion is negative (−).

2. Law of Conservation of Linear Momentum

According to Newton's third law of motion, when two objects collide in an isolated system (where external net forces ΣFext = 0), the internal forces exerted by the objects on each other are equal and opposite. Consequently:

Pinitial = Pfinal &implies; m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂

The total linear momentum of the system remains strictly constant before and after the collision.

3. Elastic vs. Inelastic Collisions

  • Elastic Collision (e = 1.0): Both total momentum and total kinetic energy are conserved. The post-collision velocities are:
    v₁ = [(m₁ - m₂)u₁ + 2m₂u₂] / (m₁ + m₂)
    v₂ = [2m₁u₁ + (m₂ - m₁)u₂] / (m₁ + m₂)
  • Perfectly Inelastic Collision (e = 0.0): Objects lock together and move at a common final velocity (vf). Maximum kinetic energy is transformed into thermal and deformation energy:
    v₁ = v₂ = vf = (m₁u₁ + m₂u₂) / (m₁ + m₂)

4. Real-World Engineering Applications

  • Automotive Safety Testing: Designing crumple zones and air-bag deployment algorithms based on collision impulse (J = Δp).
  • Ballistics & Particle Physics: Analyzing subatomic collisions in hadron colliders and recoil velocities in aerospace launch systems.
  • Orbital Gravity Assists: Leveraging planetary momentum transfer to accelerate interplanetary space probes (e.g., Voyager, James Webb).