How Do First Class Levers Apply to Scissors?

[Peter G.]

I understand the principle of moments and how it is applicable to first class levers:

A stone, at 1 m from the fulcrum weights 300N
I stand at 3 m from the fulcrum:

Clockwise Moment = Anticlockwise Moment
F x 3 = 300 x 1
Therefore, I have to exert 100N of force to lift the stone. To balance the "see-saw"

The work I do in case I want to raise it by 0.1 m will be:
I stand at 3 meters, the load at 1, so I move three times the distance, therefore, the work I do will be using the distance of 0.3 m

Therefore, Force x Distance = 100 x 0.3 = 30 Joules

However, I need to understand how a scissor works. I am assuming it consists of two first class levers. Does it work like this?

I grip the scissor at 0.1 m from the fulcrum and exert 10 N of force, providing a clockwise turning effect of 1 N/m

The object I'm trying to cut is at 0.05 m from the fulcrum. My guess is that it experiences the same turning effect, but being closer to the fulcrum it will suffer from a much greater force: 10 x 0.1 = F x 0.05 = 20 N of force.

Sorry for the long text but I think it makes it easier for you guys to help me despite being a "pain" to endure :shy:

 

[tiny-tim]

Hi Peter!

I grip the scissor at 0.1 m from the fulcrum and exert 10 N of force, providing a clockwise turning effect of 1 N/m

The object I'm trying to cut is at 0.05 m from the fulcrum. My guess is that it experiences the same turning effect, but being closer to the fulcrum it will suffer from a much greater force: 10 x 0.1 = F x 0.05 = 20 N of force.

Yes, that's right!

 

[Peter G.]

Thanks a lot Tiny-tim!