Advantage of doorknobs with long handles

[deamonvivid]

Torque question.
What is the advantage of of doorknobs with long handles instead of standard round ones in terms of decreased force requirements?

 

[learningphysics]

Torque question.
What is the advantage of of doorknobs with long handles instead of standard round ones in terms of decreased force requirements?

What is the definition of torque?

 

[deamonvivid]

the rotational motion of an object

 

[asd1249jf]

the rotational motion of an object

True.. more specifically, how is that rotational motion caused?

What is the equation for torque?

 

[learningphysics]

the rotational motion of an object

There is a definition of torque that is related to force and the distance from the rotation-axis that the force was applied...

 

[deamonvivid]

rFsin()

 

[deamonvivid]

the lever arm is the perpendicular distance from the axis of rotation to the line of action of the force

 

[deamonvivid]

thats what you talking about right

 

[learningphysics]

rFsin()

yes, exactly... so suppose I apply a certain torque with a certain force F1 at a radius r1... but then I double my r from r1 to 2r1... how much force do I need for the same torque as before (keeping the same angle)...

 

[learningphysics]

thats what you talking about right

yes exactly.

 

[deamonvivid]

twice the force as well

 

[deamonvivid]

oops, a smaller force

 

[learningphysics]

oops, a smaller force

exactly... only half the force is needed for the same torque...

 

[asd1249jf]

oops, a smaller force

Right. Apply this knowledge to your practical usage of doorknobs, the lever one VS. the turning one.

 

[deamonvivid]

but i was thinking wasn't the axis of rotation always been considered was at the hinges

 

[deamonvivid]

Ok! got it now.

 

[learningphysics]

Ok! got it now.

cool.

 

[deamonvivid]

Thanks.

 

[asd1249jf]

lol.. real time replying is awesome

 

[learningphysics]

Thanks.

no prob.

 

[learningphysics]

lol.. real time replying is awesome

lol. yup.