Turning effect of force (Moments)

[xiaomeizi]

My previous post has been removed due to some reasons.
I would like to ask another question: if a uniform metre ruler with weight of 1.2N, suspended at its mid-point from a spring balance. No other force is added to the ruler.
The reading on the spring balance is 1.2N. Am I right?

If the spring balance is move rightwards, which causes the ruler to rotate due to turning effect, will the reading on the spring balance be the same or will it vary because of the turning effect of the force.

 

[PhanthomJay]

My previous post has been removed due to some reasons.

it wasn't removed, it was combined by a mentor with your original post on the same topic.

I would like to ask another question: if a uniform metre ruler with weight of 1.2N, suspended at its mid-point from a spring balance. No other force is added to the ruler.
The reading on the spring balance is 1.2N. Am I right?

Yes, indeed.

If the spring balance is move rightwards, which causes the ruler to rotate due to turning effect, will the reading on the spring balance be the same or will it vary because of the turning effect of the force.

It will vary since it is no longer in equilibrium, since the center of mass of the meter stick is now accelerating vertically and horizontally (or tangentially and radially).

 

[xiaomeizi]

it wasn't removed, it was combined by a mentor with your original post on the same topic.Yes, indeed.
It will vary since it is no longer in equilibrium, since the center of mass of the meter stick is now accelerating vertically and horizontally (or tangentially and radially).

thanks for your reply. ' It will vary since it is no longer in equilibrium'.. But I don't really get it. i thought the only force acting downwards is the weight of the meter stick. So if the reading on the spring balance varies, is it larger than 1.2N or smaller?

 

[PhanthomJay]

thanks for your reply. ' It will vary since it is no longer in equilibrium'.. But I don't really get it. i thought the only force acting downwards is the weight of the meter stick. So if the reading on the spring balance varies, is it larger than 1.2N or smaller?

Don't forget that the stick is rotating and it is accelerating in both the tangential and radial directions. In addition to the weight force, there is a radial force in the meter stick from the centripetal acceleration. The scale reading varies from a minimum at the start to a maximum at the bottom of the circle.

 

[xiaomeizi]

Don't forget that the stick is rotating and it is accelerating in both the tangential and radial directions. In addition to the weight force, there is a radial force in the meter stick from the centripetal acceleration. The scale reading varies from a minimum at the start to a maximum at the bottom of the circle.

I think I have understood it with your clear explanation.
I am really grateful for your help.