qqp question1: A ball is thrown from the top of the building of a height of 80m. At the same instant, another ball is thrown upwards with a speed of 50m/s from the bottom of the building. At what time will both meet? question2: A stone is thrown downwards from a building 500m high. At the same time a ball is thrown upwards with an initial velocity of 5m/s. When do they meet?