Finding Tension in a Vertical Circle: A 2.0-kg Ball on a Pivot

[preluderacer]

Homework Statement

A 2.0-kg ball is attached to a light rod that is 1.2 m long. The other end of the rod is loosely pinned at a frictionless pivot. The rod is raised until it is inverted, with the ball above the pivot. The rod is released and the ball moves in a vertical circle. The tension in the rod as the ball moves through the bottom of the circle is closest to:

The Attempt at a Solution

This is one of my homework problems. I can't find an example even remotely close in my textbook. Could someone explain how to go about solving this type of problem please?

 

[The legend]

have you learned circular motion?

if yes, find the velocity of the ball at the mean position, then finding centripetal force you can solve the problem.

 

[preluderacer]

Im confused don't I need to know the radius to solve for the velocity?

 

[The legend]

you know the length of the rod, so that's good enough.

 

[preluderacer]

Im still drawing a black. A little assistance with the first step?

 

[preluderacer]

do i set mv^2/r = to mg?

 

[johnsonc007]

The normal acceleration to the curve is the tension in the rod.

 

[preluderacer]

Im still not quite getting this.

 

[The legend]

T-mg=mv^2/r

now do you get it?