Time Flowing with Falling Stick

[jordanhuh]

Mod note: deleted image that was way too large.[/color]

Homework Statement

I want to know the time flowed while the stick falls.

gravity = g
density of the stick is same so it's center of mass is l/2.
what is the T?

Homework Equations

The Attempt at a Solution

failed to do torque.

 

[Simon Bridge]

You mean - "how long does it take for the stick to fall?"
Is the point of contact a fixed pivot?

failed to do torque.

... then learn.
The subject requires an actual physics lesson - there is no shortcut - lessons are expensive for a reason.

You need to draw the forces into the diagram.
At the center of mass, gravity creates a torque.

Torque is the perpendicular component of the force times the distance.
In your case, the torque will depend on the angle.

The equation to solve is $\sum\tau = I\ddot\theta$ ... so you need to know about angular momentum as well. For the stick, pivoted about one end, $I=mL^2/3$ - where L is the length of the stick.