
<u>Explanation:</u>
Velocity of B₁ = 4.3m/s
Velocity of B₂ = -4.3m/s
For perfectly elastic collision:, momentum is conserved

where,
m₁ = mass of Ball 1
m₂ = mass of Ball 2
v₁ = initial velocity of Ball 1
v₂ = initial velocity of ball 2
v'₁ = final velocity of ball 1
v'₂ = final velocity of ball 2
The final velocity of the balls after head on elastic collision would be

Substituting the velocities in the equation

If the masses of the ball is known then substitute the value in the above equation to get the final velocity of the ball.
The more arms it has the less of a chance the prey has to swim away.
Mercury,Venus,Earth and Mars
This natural resistance is known as inertia. =)