The acceleration due to gravity practically does not change near the earth and therefore it is considered constant. If the ball is thrown not high, then it will also accelerate `9.8 m/(s^2)` (even astronauts on the ISS are affected by the acceleration of gravity of about `9.2 m/(s^2)`). How to determine the height to which the ball will rise: equate the kinetic energy at the moment of the throw to potential energy at the moment of the highest point. If you raise the ball vertically upward at speed `v`, then `m(v^2)/2 = mgh`, hence `h = (v^2)/g`, for example, if you throw the ball at speed `60 mile/h = 96.5 km/h = 26.8 meter/s` then the ball will take off to a height of `73 meter = 76.5 yards`