"""Tests for collision calculations."""
from chuk_mcp_physics.collisions import (
InelasticCollision3DRequest,
ElasticCollision3DRequest,
calculate_inelastic_collision_3d,
calculate_elastic_collision_3d,
)
class TestInelasticCollision3D:
def test_perfectly_inelastic(self):
"""Test perfectly inelastic collision (e=0)."""
request = InelasticCollision3DRequest(
mass1=1500.0,
velocity1=[20.0, 0.0, 0.0],
mass2=1200.0,
velocity2=[-15.0, 0.0, 0.0],
coefficient_of_restitution=0.0,
)
result = calculate_inelastic_collision_3d(request)
# Momentum should be conserved
p_initial = 1500.0 * 20.0 + 1200.0 * (-15.0)
p_final = 1500.0 * result.final_velocity1[0] + 1200.0 * result.final_velocity2[0]
assert abs(p_initial - p_final) < 1.0
# Significant energy loss
assert result.energy_loss > 0
assert result.energy_loss_percent > 50
def test_elastic_collision_via_cor(self):
"""Test elastic collision using e=1.0."""
request = InelasticCollision3DRequest(
mass1=0.17,
velocity1=[2.0, 0.0, 0.0],
mass2=0.17,
velocity2=[0.0, 0.0, 0.0],
coefficient_of_restitution=1.0,
)
result = calculate_inelastic_collision_3d(request)
# Energy should be conserved
assert abs(result.initial_kinetic_energy - result.final_kinetic_energy) < 0.01
assert result.energy_loss_percent < 1.0
class TestElasticCollision3D:
def test_equal_mass_head_on(self):
"""Test elastic collision with equal masses, head-on."""
request = ElasticCollision3DRequest(
mass1=0.17,
velocity1=[2.0, 0.0, 0.0],
mass2=0.17,
velocity2=[0.0, 0.0, 0.0],
)
result = calculate_elastic_collision_3d(request)
# With equal masses, velocities should exchange
assert abs(result.final_velocity1[0]) < 0.1 # Ball 1 stops
assert abs(result.final_velocity2[0] - 2.0) < 0.1 # Ball 2 moves at 2 m/s
# Energy and momentum conserved
assert abs(result.initial_kinetic_energy - result.final_kinetic_energy) < 0.01
def test_momentum_conservation(self):
"""Test momentum conservation in elastic collision."""
request = ElasticCollision3DRequest(
mass1=2.0,
velocity1=[5.0, 0.0, 0.0],
mass2=3.0,
velocity2=[-2.0, 0.0, 0.0],
)
result = calculate_elastic_collision_3d(request)
# Check momentum conservation
p_initial_x = 2.0 * 5.0 + 3.0 * (-2.0)
p_final_x = 2.0 * result.final_velocity1[0] + 3.0 * result.final_velocity2[0]
assert abs(p_initial_x - p_final_x) < 0.01
