Grip Strength: Comparing Pressure Needed to Hold 20kg Weight Plate

[jjirving]

I am interested to compare two scenarios relating to grip strength and how much horizontal pressure will be required to hold the weight.

Scenario 1: You have a 20kg weight plate in one piece. You hold the plate between your fingers.

Scenario 2: You are holding a small 2X4 block of wood with a hook on the bottom attached to a weight plate.

Assume both materials have the same surface tension, and assume both apparatus are calibrated to exactly the same weight.

Will the same pressure need to be applied to hold the weight? I don't have an answer for this other than observationally it appears significantly harder with scenario 2.

 

[berkeman]

Welcome to PF.

I am interested to compare two scenarios relating to grip strength and how much horizontal pressure will be required to hold the weight.

Scenario 1: You have a 20kg weight plate in one piece. You hold the plate between your fingers.

Scenario 2: You are holding a small 2X4 block of wood with a hook on the bottom attached to a weight plate.

Assume both materials have the same surface tension, and assume both apparatus are calibrated to exactly the same weight.

Will the same pressure need to be applied to hold the weight? I don't have an answer for this other than observationally it appears significantly harder with scenario 2.

A sketch or pictures would help to clarify what you are asking. And by "surface tension", do you mean the coefficient of friction?

 

[jjirving]

Welcome to PF.
A sketch or pictures would help to clarify what you are asking. And by "surface tension", do you mean the coefficient of friction?

I think that's what you mean. I don't have a physics background so I was hoping to get some help understanding the issue.

Scenario 1 is simply just holding the plate and we can assume the width is the same for the block as shown in the image which is the sort of setup I have for scenario 2.

 

[Ibix]

In terms of applied forces, if the coefficient of friction between your fingers and the wood is the same as that between your fingers and the metal then there is no difference in holding the apparatus in the picture by the wood (with the plate dangling) or the plate (with the wood dangling).

However, the plate has structure, and will be considerably easier to hold if your fingers are "hooked" under the rim. There is no rim to the wooden block so this cannot happen there. This would mean you'd have to apply less pinch force to the plate than you would for the same weight if it were a flat disc.

Also the plate is considerably thinner than the wooden block, and I think it's easier for your fingers to apply the same force to a thinner object than a thicker one. You could test this by looping a chain or rope through two identical plates and trying to pinch two of them stacked together or one hanging from the other (so you'd have the same weight and same coefficient of friction, but different thickness). I suspect you'll find the "one hanging" configuration easier to hold.

Also I have my doubts that the coefficient of friction is the same with the wood and the plate. The paint on the weight looks quite rough, probably as a deliberate aid to gripping it - the manufacturers don't want to drop it on your toes while you're attaching it to a bar. The wood doesn't look exactly polished, but looks to be cleanly cut and quite smooth.