physics help with kinetic energy?

Question

Two blocks are connected by a thin inextensible string
over a frictionless massless pulley. The acceleration of gravity is 9.8m/s^2


Given that the two blocks move at 3m/s under an
acceleration of 4.1 m/s^2, calculate the coefficient Mμk
of kinetic friction between the left block and the incline.

Answer 1

I'm guessing one block is sliding horizontally on a horizontal position while the other is hanging.

Use Newton's Second Law
ΣF=ma
as a starting point.

We can shortcut the problem slightly by realizing that the system accelerates together.

ΣF
=m(hanging)g-μm(sliding)g
=m(total)a

I think you have to assume that the masses of the blocks are the same, otherwise you are stuck. Cancel out the mass.

g-μg=2 a

Solve for μ and that's it.

Answer 2

There are a few holes in the story.

Is it moving at a constant 3 m/s or is it accelerating? Can't be both.
What's the masses of the blocks?
What's the incline angle?
Is the right block hanging, or maybe on a frictionless horizontal plane?

Answer 3

You'd need to know the masses of the blocks and the angle of the incline. With that information, I can do this no problem. I teach physics.
Messenger me on yahoo messenger. I am
fortitudinousskeptic
I'll help.
-kevin

Answer 4

i have no idea what that means...r u like a genious or r u obsessed with kinetic energy....although i'm young so theres another reason i'm confused....w/e....