A 1.8 kg particle-like object moves in a plane with velocity components vx = 20 m/s and vy = 50 m/s as it passes through the point with (x, y) coordinates of (3.0, -4.0) m.

Question

(a) What is its angular momentum relative to the origin at this moment?
1 kg · m2/s

(b) What is its angular momentum relative to the point (-2.0, -2.0) m at this same moment?
2 kg · m2/s

Answer 1

1(a)
r = (3 -4); p = 1.8x(20 30)
r X p = 1.8[ 3x50 - (-4x20)] = 1.8x(150 + 80)
= 1.8x230 = 414 kg m2/sec

1(b)
r = (3 - (-2), -4 - (-2)) = ( 5 -2)
similarly
r X p = 522 kg m2/sec