4. An object (Object A) with a mass of 500 kg is traveling in a straight line from west to east at a constant velocity of 34 m/s. Object A encounters a headwind blowing with a force of 25 N for six minutes and then proceeds to collide with a stationary object (Object B) with a mass of 300 kg, thereby reducing the velocity of Object A to 4 m/s. What is the final velocity of Object B?