How Does Gravity Affect Friction in the Sticky-Shoe Lab?

[anna sung]

Homework Statement

1. what happened to the amount of friction between the surface and the shoe was the force of gravity was increased?

2. when a piece of paper was placed between the shoe and the surface(table), was more force, less force, or the same force needed to pull the shoe?

Homework Equations

we had a lab in physics class. it was called a sticky-shoe lab. these are the questions i need to answer but i am not sure if my answer is correct.

The Attempt at a Solution

1. the amount of friction would increase as the force of gravity increases, because greater force of gravity means more mass . (but i am not sure how to explain that friction will increase also)

2. less force was required to pull the shoe because when a piece of paper was placed beween the shoe and the surface, the coeifficient of firction was no longer dealing with rubber on a dry surface but a sheet of paper (wood?).
( here is it correct to say that the coeifficient of friction became wood on dry surface, and would this result less friction?)

please help me :)

 

[jrab]

well for the first part assuming that this is all on a horizontal plane then would fn equal fg ? so if friction relies on fn and fn increases then...

i don't see anything wrong with your second answer

 

[anna sung]

sorry about late reply.
my internet's too slow.
anyways thanks for checking over my question. do you think i could write some more to that question. and i don't know if i am wrong but answers to those two question seems very similar. do you think there is any more stuff i could write down to elaborate more?

 

[jrab]

if you want to elaborate more about the 2nd part talk about the natures of the materials like roughness and compare them to objects like a zipper

the first part you could do a net force statement and FBD to demonstate

 

[anna sung]

okay thank you so much! :)