def test_linearmomentum():
N = ReferenceFrame("N")
Ac = Point("Ac")
Ac.set_vel(N, 25 * N.y)
I = outer(N.x, N.x)
A = RigidBody("A", Ac, N, 20, (I, Ac))
P = Point("P")
Pa = Particle("Pa", P, 1)
Pa.point.set_vel(N, 10 * N.x)
BL = [A, Pa]
assert linearmomentum(BL, N) == 10 * N.x + 500 * N.y
def test_angularmomentum_and_linearmomentum():
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))
BL = [Pa, A]
assert linearmomentum(BL, N) == 2 * m * q1d * l1 * N.y + M * l1 * q1d * N.y
assert angularmomentum(BL, O, N) == 4 * m * q1d * l1 ** 2 * N.z + q1d * N.z
