what i was trying to highlight the typo error. LOL
the applet is fine, the text in your first post seems wrong
solve the above equation will give you
f=([color=blue][size=20pt]1[/size][/color]/3)m*g*sin? for cylinder or f=([size=20pt][color=blue]2[/color][/size]/7)m*g*sin? for sphere.