A 2 kg meatball with a velocity of 5 m/s collides head-on, elastically, with a 3 kg meatball with a velocity - 5 m/s. What will be their velocities after the collision?

The horizontal blue line through the middle of the lens is called the optical axis. as the lamp is moved above or below the axis, keeping the horizontal distance to the center of the lens constant, how does the horizontal distance from the lens to the image change?