TheAlgorithms/Python · error · ValueError

Impossible fluid density

Error message

Impossible fluid density

What it means

Raised by archimedes_principle when fluid_density is <= 0. The buoyant force formula (density * gravity * volume) requires a positive fluid density; zero density would mean no fluid, and negative density is unphysical. This is the first of three ordered validation checks (density, volume, gravity).

Source

Thrown at physics/archimedes_principle_of_buoyant_force.py:50

    6844.061035
    >>> archimedes_principle(fluid_density=997, volume=-0.7)
    Traceback (most recent call last):
        ...
    ValueError: Impossible object volume
    >>> archimedes_principle(fluid_density=0, volume=0.7)
    Traceback (most recent call last):
        ...
    ValueError: Impossible fluid density
    >>> archimedes_principle(fluid_density=997, volume=0.7, gravity=0)
    0.0
    >>> archimedes_principle(fluid_density=997, volume=0.7, gravity=-9.8)
    Traceback (most recent call last):
        ...
    ValueError: Impossible gravity
    """

    if fluid_density <= 0:
        raise ValueError("Impossible fluid density")
    if volume <= 0:
        raise ValueError("Impossible object volume")
    if gravity < 0:
        raise ValueError("Impossible gravity")

    return fluid_density * gravity * volume


if __name__ == "__main__":
    import doctest

    doctest.testmod()

View on GitHub (pinned to f5988cc097)

Solutions

1. Pass a positive fluid density in kg/m^3 (e.g. 997 for water, 1.225 for air at sea level)
2. Check config defaults: an unset density of 0 will raise
3. For vacuum/free-fall scenarios, keep density/volume positive and set gravity=0 instead (that path is supported)

Example fix

# before
archimedes_principle(fluid_density=0, volume=0.7, gravity=9.8)  # ValueError

# after
archimedes_principle(fluid_density=997, volume=0.7, gravity=9.8)

def valid_fluid_density(fluid_density) -> bool:
    return fluid_density > 0

When it happens

Trigger: Calling archimedes_principle(fluid_density=-997, ...) or archimedes_principle(fluid_density=0, ...). Gravity=0 is allowed (returns 0.0, e.g. orbit); only density and volume must be strictly positive.

Common situations: Passing densities in wrong units or sign conventions, defaulting density to 0 in a config struct, or vacuum scenarios encoded as 0 density — all rejected by design.

Related errors

• Impossible object volume
• Impossible gravity
• Invalid value for min_val or max_val (min_value < max_value)
• argument value for lower and higher must be(lower > higher)
• guess value must be within the range of lower and higher val

AI-assisted analysis of TheAlgorithms/Python@f5988cc097 (2026-08-14). Data as JSON: /api/errors/c08f079554ffe236. Report an issue: GitHub.