def test_angular_momentum_and_linear_momentum():
"""A rod with length 2l, centroidal inertia I, and mass M along with a
particle of mass m fixed to the end of the rod rotate with an angular rate
of omega about point O which is fixed to the non-particle end of the rod.
The rod's reference frame is A and the inertial frame is N."""
m, M, l, I = symbols('m, M, l, I')
omega = dynamicsymbols('omega')
N = ReferenceFrame('N')
a = ReferenceFrame('a')
O = Point('O')
Ac = O.locatenew('Ac', l * N.x)
P = Ac.locatenew('P', l * N.x)
O.set_vel(N, 0 * N.x)
a.set_ang_vel(N, omega * N.z)
Ac.v2pt_theory(O, N, a)
P.v2pt_theory(O, N, a)
Pa = Particle('Pa', P, m)
A = RigidBody('A', Ac, a, M, (I * outer(N.z, N.z), Ac))
expected = 2 * m * omega * l * N.y + M * l * omega * N.y
assert linear_momentum(N, A, Pa) == expected
raises(TypeError, lambda: angular_momentum(N, N, A, Pa))
raises(TypeError, lambda: angular_momentum(O, O, A, Pa))
raises(TypeError, lambda: angular_momentum(O, N, O, Pa))
expected = (I + M * l**2 + 4 * m * l**2) * omega * N.z
assert angular_momentum(O, N, A, Pa) == expected
def test_angular_momentum_and_linear_momentum():
m, M, l1 = symbols('m M l1')
q1d = dynamicsymbols('q1d')
N = ReferenceFrame('N')
O = Point('O')
O.set_vel(N, 0 * N.x)
Ac = O.locatenew('Ac', l1 * N.x)
P = Ac.locatenew('P', l1 * N.x)
a = ReferenceFrame('a')
a.set_ang_vel(N, q1d * N.z)
Ac.v2pt_theory(O, N, a)
P.v2pt_theory(O, N, a)
Pa = Particle('Pa', P, m)
I = outer(N.z, N.z)
A = RigidBody('A', Ac, a, M, (I, Ac))
assert linear_momentum(N, A, Pa) == 2 * m * q1d* l1 * N.y + M * l1 * q1d * N.y
assert angular_momentum(O, N, A, Pa) == 4 * m * q1d * l1**2 * N.z + q1d * N.z
def test_angular_momentum_and_linear_momentum():
m, M, l1 = symbols("m M l1")
q1d = dynamicsymbols("q1d")
N = ReferenceFrame("N")
O = Point("O")
O.set_vel(N, 0 * N.x)
Ac = O.locatenew("Ac", l1 * N.x)
P = Ac.locatenew("P", l1 * N.x)
a = ReferenceFrame("a")
a.set_ang_vel(N, q1d * N.z)
Ac.v2pt_theory(O, N, a)
P.v2pt_theory(O, N, a)
Pa = Particle("Pa", P, m)
I = outer(N.z, N.z)
A = RigidBody("A", Ac, a, M, (I, Ac))
assert linear_momentum(N, A, Pa) == 2 * m * q1d * l1 * N.y + M * l1 * q1d * N.y
assert angular_momentum(O, N, A, Pa) == 4 * m * q1d * l1 ** 2 * N.z + q1d * N.z
def test_angular_momentum_and_linear_momentum():
m, M, l1 = symbols('m M l1')
q1d = dynamicsymbols('q1d')
N = ReferenceFrame('N')
O = Point('O')
O.set_vel(N, 0 * N.x)
Ac = O.locatenew('Ac', l1 * N.x)
P = Ac.locatenew('P', l1 * N.x)
a = ReferenceFrame('a')
a.set_ang_vel(N, q1d * N.z)
Ac.v2pt_theory(O, N, a)
P.v2pt_theory(O, N, a)
Pa = Particle('Pa', P, m)
I = outer(N.z, N.z)
A = RigidBody('A', Ac, a, M, (I, Ac))
assert linear_momentum(N, A, Pa) == 2 * m * q1d* l1 * N.y + M * l1 * q1d * N.y
assert angular_momentum(O, N, A, Pa) == 4 * m * q1d * l1**2 * N.z + q1d * N.z
def test_angular_momentum_and_linear_momentum():
"""A rod with length 2l, centroidal inertia I, and mass M along with a
particle of mass m fixed to the end of the rod rotate with an angular rate
of omega about point O which is fixed to the non-particle end of the rod.
The rod's reference frame is A and the inertial frame is N."""
m, M, l, I = symbols('m, M, l, I')
omega = dynamicsymbols('omega')
N = ReferenceFrame('N')
a = ReferenceFrame('a')
O = Point('O')
Ac = O.locatenew('Ac', l * N.x)
P = Ac.locatenew('P', l * N.x)
O.set_vel(N, 0 * N.x)
a.set_ang_vel(N, omega * N.z)
Ac.v2pt_theory(O, N, a)
P.v2pt_theory(O, N, a)
Pa = Particle('Pa', P, m)
A = RigidBody('A', Ac, a, M, (I * outer(N.z, N.z), Ac))
expected = 2 * m * omega * l * N.y + M * l * omega * N.y
assert linear_momentum(N, A, Pa) == expected
expected = (I + M * l**2 + 4 * m * l**2) * omega * N.z
assert angular_momentum(O, N, A, Pa) == expected
def test_angular_momentum_and_linear_momentum():
"""A rod with length 2l, centroidal inertia I, and mass M along with a
particle of mass m fixed to the end of the rod rotate with an angular rate
of omega about point O which is fixed to the non-particle end of the rod.
The rod's reference frame is A and the inertial frame is N."""
m, M, l, I = symbols("m, M, l, I")
omega = dynamicsymbols("omega")
N = ReferenceFrame("N")
a = ReferenceFrame("a")
O = Point("O")
Ac = O.locatenew("Ac", l * N.x)
P = Ac.locatenew("P", l * N.x)
O.set_vel(N, 0 * N.x)
a.set_ang_vel(N, omega * N.z)
Ac.v2pt_theory(O, N, a)
P.v2pt_theory(O, N, a)
Pa = Particle("Pa", P, m)
A = RigidBody("A", Ac, a, M, (I * outer(N.z, N.z), Ac))
expected = 2 * m * omega * l * N.y + M * l * omega * N.y
assert (linear_momentum(N, A, Pa) - expected) == Vector(0)
expected = (I + M * l ** 2 + 4 * m * l ** 2) * omega * N.z
assert (angular_momentum(O, N, A, Pa) - expected).simplify() == Vector(0)