Explanation:
Given
initial speed(u)=3 m/s
mass of each ball is m
Let the cue ball is moving in x direction initially
In elastic collision Energy and momentum is conserved
Let u be the initial velocity and
be the final velocity of 8 ball and cue ball respectively

The angle after which cue ball is deflected is given by

Conserving momentum in x direction


Along Y axis


substitute the value of 
we get 

Answer:
The weight is the gravitational force with which a body is attached to the Earth (planet/moon) Weight of any object on earth depends on two factors mass and gravitational constant. As per law, W = mg where, g is gravitational constant 9.8 m/s/s