[" rotational motion "],[" 13.Two particles "A" and "B" are moving as shown in the figure."],[[6.5times8],[1.5]]],[" Their total angular momentum about the point "O" is "],[[" (a) "9.8kgm^(2)s^(-1)," (b) zero "],[" (c) "52.7kgm^(2)s^(-1)," (d) "37.9kgm^(2)s^(-1)]]