"""Tests for enhanced projectile motion features (Magnus force, wind, altitude)."""
from chuk_mcp_physics.models import ProjectileWithDragRequest
from chuk_mcp_physics.kinematics import calculate_projectile_with_drag
class TestMagnusForce:
"""Test Magnus force (spin effects) on projectiles."""
def test_backspin_increases_range(self):
"""Test that backspin increases range (like baseball/golf)."""
# Baseball with no spin
no_spin = ProjectileWithDragRequest(
initial_velocity=40.23,
angle_degrees=15,
mass=0.145,
drag_coefficient=0.4,
cross_sectional_area=0.0043,
spin_rate=0.0,
)
# Baseball with backspin (2500 rpm = 261.8 rad/s)
with_backspin = ProjectileWithDragRequest(
initial_velocity=40.23,
angle_degrees=15,
mass=0.145,
drag_coefficient=0.4,
cross_sectional_area=0.0043,
spin_rate=261.8, # 2500 rpm
spin_axis=[0, 0, 1], # Backspin (z-axis perpendicular to motion)
)
result_no_spin = calculate_projectile_with_drag(no_spin)
result_backspin = calculate_projectile_with_drag(with_backspin)
# Backspin should increase range and max height
assert result_backspin.range > result_no_spin.range
assert result_backspin.max_height > result_no_spin.max_height
assert result_backspin.magnus_force_max > 0
def test_sidespin_lateral_deflection(self):
"""Test that sidespin causes lateral deflection."""
# Soccer ball with sidespin
with_sidespin = ProjectileWithDragRequest(
initial_velocity=25.0,
angle_degrees=15,
mass=0.43,
drag_coefficient=0.25,
cross_sectional_area=0.0388,
spin_rate=100.0, # rad/s
spin_axis=[0, 1, 0], # Horizontal spin axis
)
result = calculate_projectile_with_drag(with_sidespin)
# Should have lateral deflection
assert result.lateral_deflection > 0
assert result.magnus_force_max > 0
def test_no_spin_no_magnus(self):
"""Test that zero spin produces no Magnus force."""
no_spin = ProjectileWithDragRequest(
initial_velocity=30.0,
angle_degrees=45,
mass=1.0,
drag_coefficient=0.47,
cross_sectional_area=0.01,
spin_rate=0.0,
)
result = calculate_projectile_with_drag(no_spin)
# No spin = no Magnus force = no lateral deflection
assert result.magnus_force_max == 0.0
assert result.lateral_deflection == 0.0
class TestWindEffects:
"""Test wind effects on projectile motion."""
def test_tailwind_increases_range(self):
"""Test that tailwind increases range."""
# No wind
no_wind = ProjectileWithDragRequest(
initial_velocity=30.0,
angle_degrees=45,
mass=1.0,
drag_coefficient=0.47,
cross_sectional_area=0.01,
wind_velocity=[0.0, 0.0],
)
# 10 m/s tailwind
tailwind = ProjectileWithDragRequest(
initial_velocity=30.0,
angle_degrees=45,
mass=1.0,
drag_coefficient=0.47,
cross_sectional_area=0.01,
wind_velocity=[10.0, 0.0],
)
result_no_wind = calculate_projectile_with_drag(no_wind)
result_tailwind = calculate_projectile_with_drag(tailwind)
# Tailwind should increase range
assert result_tailwind.range > result_no_wind.range
assert result_tailwind.wind_drift > 0
def test_headwind_decreases_range(self):
"""Test that headwind decreases range."""
# No wind
no_wind = ProjectileWithDragRequest(
initial_velocity=30.0,
angle_degrees=45,
mass=1.0,
drag_coefficient=0.47,
cross_sectional_area=0.01,
wind_velocity=[0.0, 0.0],
)
# 10 m/s headwind
headwind = ProjectileWithDragRequest(
initial_velocity=30.0,
angle_degrees=45,
mass=1.0,
drag_coefficient=0.47,
cross_sectional_area=0.01,
wind_velocity=[-10.0, 0.0],
)
result_no_wind = calculate_projectile_with_drag(no_wind)
result_headwind = calculate_projectile_with_drag(headwind)
# Headwind should decrease range
assert result_headwind.range < result_no_wind.range
assert result_headwind.wind_drift < 0
def test_updraft_increases_height(self):
"""Test that updraft increases max height."""
# No wind
no_wind = ProjectileWithDragRequest(
initial_velocity=30.0,
angle_degrees=45,
mass=1.0,
drag_coefficient=0.47,
cross_sectional_area=0.01,
wind_velocity=[0.0, 0.0],
)
# 5 m/s updraft
updraft = ProjectileWithDragRequest(
initial_velocity=30.0,
angle_degrees=45,
mass=1.0,
drag_coefficient=0.47,
cross_sectional_area=0.01,
wind_velocity=[0.0, 5.0],
)
result_no_wind = calculate_projectile_with_drag(no_wind)
result_updraft = calculate_projectile_with_drag(updraft)
# Updraft should increase max height and time of flight
assert result_updraft.max_height > result_no_wind.max_height
assert result_updraft.time_of_flight > result_no_wind.time_of_flight
class TestAltitudeEffects:
"""Test altitude and temperature effects on air density."""
def test_high_altitude_less_drag(self):
"""Test that high altitude reduces air density and drag."""
# Sea level
sea_level = ProjectileWithDragRequest(
initial_velocity=70.0,
angle_degrees=12,
mass=0.0459, # Golf ball
drag_coefficient=0.25,
cross_sectional_area=0.00143,
altitude=0.0,
temperature=15.0,
)
# Denver altitude (1600m)
high_altitude = ProjectileWithDragRequest(
initial_velocity=70.0,
angle_degrees=12,
mass=0.0459,
drag_coefficient=0.25,
cross_sectional_area=0.00143,
altitude=1600.0,
temperature=15.0,
)
result_sea_level = calculate_projectile_with_drag(sea_level)
result_high_altitude = calculate_projectile_with_drag(high_altitude)
# High altitude = less air density = less drag = longer range
assert result_high_altitude.effective_air_density < result_sea_level.effective_air_density
assert result_high_altitude.range > result_sea_level.range
assert result_high_altitude.energy_lost_to_drag < result_sea_level.energy_lost_to_drag
def test_hot_temperature_less_drag(self):
"""Test that hot temperature reduces air density."""
# Cold day
cold = ProjectileWithDragRequest(
initial_velocity=30.0,
angle_degrees=45,
mass=1.0,
drag_coefficient=0.47,
cross_sectional_area=0.01,
altitude=0.0,
temperature=0.0, # 0°C
)
# Hot day
hot = ProjectileWithDragRequest(
initial_velocity=30.0,
angle_degrees=45,
mass=1.0,
drag_coefficient=0.47,
cross_sectional_area=0.01,
altitude=0.0,
temperature=30.0, # 30°C
)
result_cold = calculate_projectile_with_drag(cold)
result_hot = calculate_projectile_with_drag(hot)
# Hot air = less dense = less drag = longer range
assert result_hot.effective_air_density < result_cold.effective_air_density
assert result_hot.range > result_cold.range
def test_effective_density_calculation(self):
"""Test that effective air density is calculated correctly."""
# Sea level, 15°C should be close to standard 1.225 kg/m³
standard = ProjectileWithDragRequest(
initial_velocity=30.0,
angle_degrees=45,
mass=1.0,
drag_coefficient=0.47,
cross_sectional_area=0.01,
altitude=0.0,
temperature=15.0,
)
result = calculate_projectile_with_drag(standard)
# Should be very close to standard air density
assert abs(result.effective_air_density - 1.225) < 0.1
class TestCombinedEffects:
"""Test combinations of enhancements."""
def test_golf_ball_with_all_effects(self):
"""Test golf ball with backspin, wind, and altitude."""
# Golf drive with all effects
golf = ProjectileWithDragRequest(
initial_velocity=70.0,
angle_degrees=12,
mass=0.0459,
drag_coefficient=0.25,
cross_sectional_area=0.00143,
spin_rate=200.0, # Backspin
spin_axis=[0, 0, 1],
wind_velocity=[3.0, 0.0], # Tailwind
altitude=1000.0, # Moderate altitude
temperature=25.0, # Warm day
)
result = calculate_projectile_with_drag(golf)
# All effects should contribute to longer range
assert result.range > 140 # meters
assert result.magnus_force_max > 0
assert result.wind_drift > 0
assert result.effective_air_density < 1.225
def test_baseball_curveball(self):
"""Test baseball curveball with spin and realistic conditions."""
# Curveball with topspin (drops faster)
curveball = ProjectileWithDragRequest(
initial_velocity=35.0, # 78 mph
angle_degrees=5,
mass=0.145,
drag_coefficient=0.4,
cross_sectional_area=0.0043,
spin_rate=200.0, # Topspin
spin_axis=[0, 0, -1], # Negative z = topspin
temperature=20.0,
)
result = calculate_projectile_with_drag(curveball)
# Should have significant Magnus force
assert result.magnus_force_max > 0
# Range should be reasonable for curveball
assert 10 < result.range < 20
