The formula for calculating the ball speed at the top of a 38.8m building is speed = distance/time. In this case, the distance is 13m and the time is 2 seconds, so the ball speed would be 6.5 meters per second.
The distance is measured using a measuring tape or ruler, while the time is measured using a stopwatch or timer. Both measurements should be taken accurately to ensure reliable results.
There are a few factors that can affect the ball speed at the top of the building. These include air resistance, wind, and the initial force or velocity at which the ball is thrown. In this experiment, we assume that the ball is thrown with a constant initial velocity and there is no wind or air resistance.
To test different heights, the same experiment can be repeated using buildings of different heights. To test different times, the distance and velocity of the ball can be adjusted accordingly. For example, if we want to measure the ball speed at the top of a 20m building in 4 seconds, the initial velocity of the ball should be increased to cover the distance in 4 seconds.
Some potential sources of error in this experiment include human error in measuring the distance and time, variations in the initial velocity of the ball, and external factors such as wind or air resistance. It is important to repeat the experiment multiple times and take accurate measurements to minimize these errors.