Please let me know how should I proceed further.
World of Alphabets is an android app which teaches English Alphabets. It uses text to speech feature of android framework. The .apk file for the app can be downloaded from: https://github.com/beginnee/APK_of_WorldofAlphabets
a) Good and Bad Friction: https://github.com/beginnee/Good-and-bad-friction
This tutorial allows user to distinguish between good friction and bad friction. Good friction is the friction which has some usefulness and bad friction is the one that just increases the costs.
b) Types of Friction: https://github.com/beginnee/Types_of_friction
This is an interactive tutorial showing the two types of friction, sliding friction and rolling friction. It shows how the frictional force vary with the angle of inclination and the amount of surface area in contact.
c) Frictional force and area: https://github.com/beginnee/Frictionalforce_and_area
This tutorial depicts the relationship of frictional force offered by a surface to the area of the object that is in contact with the surface.
d) Multiple forces and direction of frictional force: https://github.com/beginnee/Multiple_forces-direction_and_result
This tutorial depicts the relationship of frictional force offered by a surface with multiple forces. It shows how the direction of frictional force change with the change in the direction of the applied forces.
Thanks