a ball is thrown vertically upward with an initial velocity of 53 feet per second. in the first 1.5 seconds, it travels 42 feet. The formula is s = (u/+v/2)t. represents the vertical distance s that an object travels in t seconds, where u represents the initial velocity of the object and v represents the velocity of the object at the end of t seconds. Find the velocity of the ball at the end of 1.5 seconds.