Centripetal Force and Force due to gravity?

[wooker]

Homework Statement

So I'm doing a lab of examining circular motion and centripetal force. My results came out to be that as Fg increases, Fc decreases. My question is if this relationship between Fg and Fc is logical and why?

The experiment was conducted in a way that a ball was attached to a string and whirled on a horizontal plane at constant velocity. There was also a variable of hanging mass so, increasing mass and increasing Fg with decreasing Fc.

Homework Equations

The Attempt at a Solution

 

[The legend]

in what manner are you doing the experiment? In which plane?

 

[The legend]

ok, so...

if we use the theoretical approach..

Fc = mv²/r
and if Fg increases and the mass increases too(as you said),...Fc also increases.

But i don't really see how Fg influences Fc, because this is all dependent on mass and not weight.

 

[PhanthomJay]

Fc = mv²/r
and if Fg increases and the mass increases too(as you said),...Fc also increases.

That is certainly true if the speed in both cases remains the same.

The experiment was conducted in a way that a ball was attached to a string and whirled on a horizontal plane at constant velocity. There was also a variable of hanging mass so, increasing mass and increasing Fg with decreasing Fc.

Did the heavier mass cause the angle between the string and the vertical to be smaller than the angle between the string and the vertical when you used the lighter mass? Did the radius of the horizontal circle change? How did you do your measuremnts and calculate the centripetal force?