Re: What forces affect a ball bearing in jelly?

Initially before the ball bearing reaches the jelly it is being 
accelerated by gravity, the force due to gravity being = mg (newtons laws)
The only resistance to it's motion is drag due to air resistance.

As the ball bearing enters the jelly it fistly has to overcome any surface 
tension. Within the jelly there is a greater drag on the ball bearing as 
the jelly is denser and more viscous than air.

As density of the jelly increases the drag will also increase - though 
probably not in a linear fashion. Other properties of the jelly will also 
contribute to it's frictional properties.

There will be a bouyancy force acting on the ball bearing, due to the 
displacement of jelly (archimedes principle)

In addition as the ball bearing moves deeper into the jelly, the amount of 
jelly above the ball bearing will increase giving a downward force. The 
magnitude of this force will depend on the density of the jelly, and 
diameter of the ball bearing.
total mass of column of jelly above ball bearing = 
density of jelly*cross sectional area of ball bearing*depth of ball bearing
the force due to this effect will therefore be = mass of column*g

take a look at
FORCES - http://www.ronkurtus.com/phy
scien/forces.htm

WORK AGAINST A RESISTIVE FORCE - http://www.ronkurtus.com/physc
ien/work.htm

RESISTIVE FORCE OF FRICTION http://www.ronkurtus.com/p
hyscien/friction.htm

FORCES IN FLUIDS - http://www.ronkurtus.com/phy
scien/fluids.htm

key search words are - Newton, Archimedes, gravity, forces, friction, drag
[Moderator note:  Another keyword would be pressure.]