static and kinetic friction

I have a lab question that I'm confused about:

What can you say about acceleration if the:

a) static coefficient = kinetic coefficient = 0
b) static coefficient = kinetic coefficient does not equal 0
c) static coefficient is greater than kinetic coefficient

 

Log in or Sign up to hide all adverts.

You have to figure out the forces acting on the body after you deal with the coefficients of friction. Once you have that then you can figure out acceleration.

 

Log in or Sign up to hide all adverts.

Slayerdeus,

I think your question is more general.

a - 'a' = F/m

b - 'a' < F/m = (F*kinetic - static)/m

c - This one is more complicated but I would think the expression would look simular.

Note: I am not a mathematician but I think you are looking for some simple expression.

Perhaps others here will advance a better version.

 

Log in or Sign up to hide all adverts.

For the last one:

'a' - << F/m when object starts at rest and 'a' - < F/m when its moving.

 

Its a cart attatched by string to a pully system and at the end is a hanger. We do four runs. One with 60 grams on the cart, 0g on hanger, measure the change in velocity, one run with 40g on cart, 20g on hanger measure, one with 20g on cart, 40g on hanger, meansure, then one with 0g on the cart and 60g on the hanger. If I knew how to attach an image I would do that.