If the mass is in circular motion, then the tension .

What if we increase the tension so that .

Will the mass moving inward() or moving outward()?

Thank about it and then check with your equation!

[/quote]

I see I got the sign convention wrong!

I forgot the convention for r unit vector is positive outward.

Will change it to

T1 = m*v*v/r -(cst*cst/(m*r*r*r)-M*g) ;

thanks !!! :)

your masterful questioning allows to think and figure out the answer myself.

Appreciate your superb advise :)

my remixed applet is here

http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=1883.0

enjoy!