Python/physics/in_static_equilibrium.py
Tianyi Zheng a8b6bda993
Delete arithmetic_analysis/ directory and relocate its contents (#10824)
* Remove eval from arithmetic_analysis/newton_raphson.py

* Relocate contents of arithmetic_analysis/

Delete the arithmetic_analysis/ directory and relocate its files because
the purpose of the directory was always ill-defined. "Arithmetic
analysis" isn't a field of math, and the directory's files contained
algorithms for linear algebra, numerical analysis, and physics.

Relocated the directory's linear algebra algorithms to linear_algebra/,
its numerical analysis algorithms to a new subdirectory called
maths/numerical_analysis/, and its single physics algorithm to physics/.

* updating DIRECTORY.md

---------

Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
2023-10-23 09:31:30 +02:00

95 lines
2.5 KiB
Python

"""
Checks if a system of forces is in static equilibrium.
"""
from __future__ import annotations
from numpy import array, cos, cross, float64, radians, sin
from numpy.typing import NDArray
def polar_force(
magnitude: float, angle: float, radian_mode: bool = False
) -> list[float]:
"""
Resolves force along rectangular components.
(force, angle) => (force_x, force_y)
>>> import math
>>> force = polar_force(10, 45)
>>> math.isclose(force[0], 7.071067811865477)
True
>>> math.isclose(force[1], 7.0710678118654755)
True
>>> force = polar_force(10, 3.14, radian_mode=True)
>>> math.isclose(force[0], -9.999987317275396)
True
>>> math.isclose(force[1], 0.01592652916486828)
True
"""
if radian_mode:
return [magnitude * cos(angle), magnitude * sin(angle)]
return [magnitude * cos(radians(angle)), magnitude * sin(radians(angle))]
def in_static_equilibrium(
forces: NDArray[float64], location: NDArray[float64], eps: float = 10**-1
) -> bool:
"""
Check if a system is in equilibrium.
It takes two numpy.array objects.
forces ==> [
[force1_x, force1_y],
[force2_x, force2_y],
....]
location ==> [
[x1, y1],
[x2, y2],
....]
>>> force = array([[1, 1], [-1, 2]])
>>> location = array([[1, 0], [10, 0]])
>>> in_static_equilibrium(force, location)
False
"""
# summation of moments is zero
moments: NDArray[float64] = cross(location, forces)
sum_moments: float = sum(moments)
return abs(sum_moments) < eps
if __name__ == "__main__":
# Test to check if it works
forces = array(
[
polar_force(718.4, 180 - 30),
polar_force(879.54, 45),
polar_force(100, -90),
]
)
location: NDArray[float64] = array([[0, 0], [0, 0], [0, 0]])
assert in_static_equilibrium(forces, location)
# Problem 1 in image_data/2D_problems.jpg
forces = array(
[
polar_force(30 * 9.81, 15),
polar_force(215, 180 - 45),
polar_force(264, 90 - 30),
]
)
location = array([[0, 0], [0, 0], [0, 0]])
assert in_static_equilibrium(forces, location)
# Problem in image_data/2D_problems_1.jpg
forces = array([[0, -2000], [0, -1200], [0, 15600], [0, -12400]])
location = array([[0, 0], [6, 0], [10, 0], [12, 0]])
assert in_static_equilibrium(forces, location)
import doctest
doctest.testmod()