Physics is the study of matter and energy and their behaviour with eachother. When investigating how an object falls you need to understand the conditions taking place. Free fall occurs when weight is the only force acting on the object (gravity is the only acceleration). This doesn't happen on earth because we have air which creates a resitive force on the object (the object is bombarded with air particles), known as drag or air resistance. Air resistance/drag and free fall are important for understanding physics because they are conditions which affect the behaviour of an object. The goal of physicists is to undertand the behaviour of said objects, therefore it is important to understand these theories.
I hope this was helpful and good luck with your report.