Physics Question

[Kisze]

So I've got a metal rod with mass 5 kg and length 2 meters leaning against a vertical wall. At the top of the rod there is a wheel or something which removes the upward static friction between the rod and the wall. Between the bottom end of the rod and the floor the friction coefficient is 0.4 and the rod is at the point where it almost starts to glide along the floor.

First off I calculated the normal force from the wall on the top of the rod which I got to 19.6 N since because it's in equilibrium, the normal force from the wall on the top of the rod has to be canceled out by the friction between the bottom of the rod and the floor. The friction is of course calculated by multiplying the normal force from the floor on the bottom of the rod by the friction coefficient. And the normal force on the bottom of the rod from the floor has to equal the weight of the rod (to cancel it out), so I got weight of the rod * coefficient of friction = normal force from the wall on the top of the rod, which is 19.6.

However, how can I calculate the angle between the wall and the top of the rod? Hints will be appreciated.

 

[Doomination]

use torque

 

[Kisze]

Oh wow, how could I forget about torque? :| It must be late... I knew I was missing something. I'll see if I can figure this out now. Thanks.

 

[No Limit]

Grab a ruler and go measure it. Duh

 

[Kisze]

Why didn't I look at your reply before calculating everything, No Limit?! Ah well. I calculated it using torque and I think I got the right answer so this topic seems pretty useless now unless someone would want a discussion of the solution or something.

 

[No Limit]

Your knowledge turns me on, in a totally non gay way.

 

[Vegeta897]

Will it take off?

 

[Doomination]

yep, no problem

 

[Maestro]

You need to use rotational motion to figure this out, dude. Don't listen to anyone else.

 

[JUL3]

So I've got a metal rod-

Grab a ruler and go measure it. Duh