## College Physics (4th Edition)

Particle B must be located at $(8.0~cm, 20.0~cm)$
We can find particle B's x-coordinate: $x_{com} = \frac{(30.0~g)(0)+(10.0~g)(x_B)}{30.0~g+10.0~g}$ $2.0~cm = \frac{0+(10.0~g)(x_B)}{40.0~g}$ $2.0~cm = \frac{x_B}{4}$ $x_B = 8.0~cm$ We can find particle B's y-coordinate: $y_{com} = \frac{(30.0~g)(0)+(10.0~g)(y_B)}{30.0~g+10.0~g}$ $5.0~cm = \frac{0+(10.0~g)(y_B)}{40.0~g}$ $5.0~cm = \frac{y_B}{4}$ $y_B = 20.0~cm$ Particle B must be located at $(8.0~cm, 20.0~cm)$.