Friction between cart and a surface covered with a liquid?

[Phys112]

<< Thread moved from the technical forums so no Homework Help Template is shown >>

Hello,

I'm attempting an experiment where I take a cart and slide it down a ramp. Each time, I will coat the ramp with a different liquid. I want to compare the effects of the dry ramp, a ramp with water poured on it, syrup/honey poured on it, etc. I can't find much information on this type of physics so I'm wondering if there are any equations I can use to help me show the math behind my data.

Thank you

 

[berkeman]

Hello,

I'm attempting an experiment where I take a cart and slide it down a ramp. Each time, I will coat the ramp with a different liquid. I want to compare the effects of the dry ramp, a ramp with water poured on it, syrup/honey poured on it, etc. I can't find much information on this type of physics so I'm wondering if there are any equations I can use to help me show the math behind my data.

Thank you

Welcome to the PF.

Can you say what you have found so far about changes in friction and in the viscious nature and thickness of this liquid coating? What have you found so far?

Also, is this for schoolwork or for a school lab experiment?

 

[Phys112]

This is for a school experiment, but it isn't assigned by the teacher, it's up to us to design an experiment. I haven't done the experiment yet, as I'm trying to figure out if I'll be able to find the mathematical stuff to write a full paper on this

 

[berkeman]

Okay, then I'll move it to our schoolwork forums where it belongs, and you can post what you find in your reading about the effects of different liquids on friction and viscosity.

So to start, what would be the difference in the cart's final speed at the bottom of the ramp if the ramp had a very thin coating of a very low friction material like Tefloe, versus a thick coating of syrup, versus no coating at all? Assume the ramp and wheels are both wood, so normal behavior would be for the wheels to turn as the cart rolls down the ramp...

 

[Phys112]

Okay, then I'll move it to our schoolwork forums where it belongs, and you can post what you find in your reading about the effects of different liquids on friction and viscosity.

So to start, what would be the difference in the cart's final speed at the bottom of the ramp if the ramp had a very thin coating of a very low friction material like Tefloe, versus a thick coating of syrup, versus no coating at all? Assume the ramp and wheels are both wood, so normal behavior would be for the wheels to turn as the cart rolls down the ramp...

Well I know the velocity will be greater for the low friction material. (I'm unsure as to whether a ramp with water would make the cart go faster than a dry one). And the syrup one would go much slower.

 

[berkeman]

Well I know the velocity will be greater for the low friction material. (I'm unsure as to whether a ramp with water would make the cart go faster than a dry one). And the syrup one would go much slower.

Will the cart's speed be faster or slower if the wheels spin or slip? Why? Can you show us the math?

 

[haruspex]

I know the velocity will be greater for the low friction material

It might be greater, but not necessarily.
And you need to be careful not to confuse friction with rolling resistance. See if section 4 here helps: https://www.physicsforums.com/insights/frequently-made-errors-mechanics-friction/