A 30 g ball is fired horizontally with initial speed v0 toward a 85 g ball that is hanging motionless from a 1.2 m long string. The balls undergo a head-on perfectly elastic collision after which the?

After the collision, the 30 g ball will come to a stop as it transfers its entire momentum to the 85 g ball, causing it to swing upwards. The final velocity of the 85 g ball can be calculated using conservation of momentum and conservation of energy principles. The maximum height the 85 g ball will reach can also be determined by equating the initial kinetic energy of the system to the potential energy at the maximum height reached.