calculate_drag_force
Calculate drag force on objects moving through fluids using velocity, area, density, and drag coefficient inputs. Returns force vector, magnitude, and Reynolds number for physics analysis.
Instructions
Calculate drag force for an object moving through a fluid.
The drag force opposes motion and is given by:
F_drag = 0.5 * ρ * v² * C_d * A
Common drag coefficients:
- Sphere: 0.47
- Streamlined shape: 0.04
- Flat plate (perpendicular): 1.28
- Human (standing): 1.0-1.3
- Car: 0.25-0.35
Args:
velocity: Velocity vector [x, y, z] in m/s (or JSON string)
cross_sectional_area: Area perpendicular to flow in m²
fluid_density: Fluid density in kg/m³ (water=1000, air=1.225)
drag_coefficient: Drag coefficient (default 0.47 for sphere)
viscosity: Dynamic viscosity in Pa·s (water=1.002e-3, air=1.825e-5, oil=0.1).
If not provided, estimated from fluid_density for Reynolds number calculation.
Returns:
Drag force vector, magnitude, and Reynolds number
Example - Ball falling through water:
result = await calculate_drag_force(
velocity=[0, -5.0, 0],
cross_sectional_area=0.00785, # π * (0.05m)² for 10cm diameter
fluid_density=1000, # water
drag_coefficient=0.47,
viscosity=1.002e-3 # water viscosity for accurate Reynolds number
)
# Returns upward drag force opposing downward motion
Example - Ball falling through motor oil:
result = await calculate_drag_force(
velocity=[0, -2.0, 0],
cross_sectional_area=0.00785,
fluid_density=900, # oil
drag_coefficient=0.47,
viscosity=0.1 # motor oil is much more viscous
)Input Schema
TableJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| velocity | Yes | ||
| cross_sectional_area | Yes | ||
| fluid_density | Yes | ||
| drag_coefficient | No | ||
| viscosity | No |