Calculus is used in many fields including physics, engineering, economics, statistics, and medicine. It is used to create mathematical models and arrive at optimal solutions. For example, in physics, many concepts are based on calculus. Weather prediction also uses calculus-based computer modeling to more accurately predict weather based on variables like temperature, wind speed, and moisture levels. The spread of infectious diseases can also be modeled using calculus to determine how far and fast a disease may spread based on susceptible, infected, and recovered populations. Calculus is widely applied in engineering fields from civil to mechanical engineering to analyze structures, fluids, thermal systems, and more.