A26.0 g ball is fired horizontally with initial speed v0 toward a 110 g ball that is hanging motionless from a 1.10 m -long string. the balls undergo a head-on, perfectly elastic collision, after which the 110 g ball swings out to a maximum angle θmax = 50.0. what was v0?

i think you need to find the tangential velocity using the angle that the ball swings to, but i am not sure how to go about beginning this problem.

Explanation:

Consider the motion of the ball attached to string.

In triangle ABD

height gained by the ball is given as

 = mass of the ball attached to string = 110 g

= speed of the ball attached to string just after collision

Using conservation of energy

Potential energy gained = Kinetic energy lost

Consider the collision between the two balls

 = mass of the ball fired = 26 g

= initial velocity of ball fired before collision = ?

= final velocity of ball fired after collision = ?

using conservation of momentum

Using conservation of kinetic energy

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.