A ball suspended from a string that goes through a hole in

the ceiling at O moves with velocity in a horizontal circular

path of radius The string is then drawn through the hole until

the ball moves with velocity in a horizontal circular path of ra$-$

dius Use the principle of angular impulse and momentum to

show that

Strategy: Let e be a unit vector that is perpendicular to the

ceiling. Although this is not a central$-$force problem$$the ball$$s

weight does not point toward O$$you can show that

so that is conserved. e e # HO # $1$r $*$F$2=0,$

rAvA $=$ rBvB$.$

rB$.$

vB

rA$.$

vA

O