Added the algorithm to compute the terminal velocity of an object fal…

physics/terminal_velocity.py

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+"""
+Title : Computing the terminal velocity of an object falling
+        through a fluid.
+
+Terminal velocity is defined as the highest velocity attained by an
+object falling through a fluid. It is observed when the sum of drag force
+and buoyancy is equal to the downward gravity force acting on the
+object. The acceleration of the object is zero as the net force acting on
+the object is zero.
+
+Vt = ((2 * m * g)/(ρ * A * Cd))^0.5
+
+where :
+Vt = Terminal velocity (in m/s)
+m = Mass of the falling object (in Kg)
+g = Acceleration due to gravity (value taken : imported from scipy)
+ρ = Density of the fluid through which the object is falling (in Kg/m^3)
+A = Projected area of the object (in m^2)
+Cd = Drag coefficient (dimensionless)
+
+Reference : https://byjus.com/physics/derivation-of-terminal-velocity/
+"""
+
+from scipy.constants import g
+
+
+def terminal_velocity(
+    mass: float, density: float, area: float, drag_coefficient: float
+) -> float:
+    """
+    >>> terminal_velocity(1, 25, 0.6, 0.77)
+    1.3031197996044768
+    >>> terminal_velocity(2, 100, 0.45, 0.23)
+    1.9467947148674276
+    >>> terminal_velocity(5, 50, 0.2, 0.5)
+    4.428690551393267
+    >>> terminal_velocity(-5, 50, -0.2, -2)
+    Traceback (most recent call last):
+        ...
+    ValueError: mass, density, area and the drag coefficient all need to be positive
+    >>> terminal_velocity(3, -20, -1, 2)
+    Traceback (most recent call last):
+        ...
+    ValueError: mass, density, area and the drag coefficient all need to be positive
+    >>> terminal_velocity(-2, -1, -0.44, -1)
+    Traceback (most recent call last):
+        ...
+    ValueError: mass, density, area and the drag coefficient all need to be positive
+    """
+    if mass <= 0 or density <= 0 or area <= 0 or drag_coefficient <= 0:
+        raise ValueError(
+            "mass, density, area and the drag coefficient all need to be positive"
+        )
+    return ((2 * mass * g) / (density * area * drag_coefficient)) ** 0.5
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()