I am looking for references and free online books of solved problems in these topics: applications of differential equations in geometry, percentage calculus, physics and geometric analysis. By applications in geometry I mean something like this: http://tutorial.math.lamar.edu/Classes/CalcI/IntAppsIntro.aspx article about applications of integrals (something of that difficulty). By applications in physics I mean simple classical mechanics (velocity, acceleration,...), combined with geometric representation. Applications in percentage calculus should also include geometric representation. Could someone suggest some good references and free online books with solved problems?