Calculus finds the relationship between the distance traveled and the speed — easy for constant speed, not so easy for changing speed. Professor Strang is finding the "rate of change" and the "slope of a curve" and the "derivative of a function." View the complete course at: http://ocw.mit.edu/OcwWeb/resources/RES-18-005Spring-2010/ResourceHome/index.htm License: Creative Commons BY-NC-SA More information at http://ocw.mit.edu/terms More courses at http://ocw.mit.edu