Masses on inclined planes and pulleys

[Patra]

1. Two objects are connected via a pulley and some string. The 12 kg cart is on a frictionless 42 deg. incline while the 15kg block is on a horizontal surface having a coefficient of friction equal to 0.23. Determine the acceleration of the system of masses.



2. Fnet=ma



3. I first tried making a FBD for the 15kg mass, but I'm not sure how I should incorporate the other mass into the diagram. Also, because the mass on the horizontal surface is heavier AND is on a frictional surface, and the mass on the incline weighs less, wouldn't the system not move at all?

Thanks in advance for any help. I find that I don't respond very well to my instructor's teaching style, but I'm trying to make the best of it.

 

[PhanthomJay]

Hi, Patra, welcome to Physics Forums!

1. Two objects are connected via a pulley and some string. The 12 kg cart is on a frictionless 42 deg. incline while the 15kg block is on a horizontal surface having a coefficient of friction equal to 0.23. Determine the acceleration of the system of masses.[/b]



2. Fnet=ma



3. I first tried making a FBD for the 15kg mass,

Please show what equation you came up with, using Newton's 2nd law.

but I'm not sure how I should incorporate the other mass into the diagram.

make a separate Free Body diagram of the mass on the incline, choosing the x-axis paralle to the incline. What equation do you get using Newton's 2nd Law?

Also, because the mass on the horizontal surface is heavier AND is on a frictional surface, and the mass on the incline weighs less, wouldn't the system not move at all?

that is a possibility, if the mass on the incline was light enough. Write your equations to find out. What 2 equations do you get when you apply Newton 2 to each block separately?

 

[ashishsinghal]

Also, because the mass on the horizontal surface is heavier AND is on a frictional surface, and the mass on the incline weighs less, wouldn't the system not move at all?

That is just a possibility. You have to check it.
Now if the pulley is massless and smooth (have to assume if not given) then tension in the string would be uniform. Make separate FBD. Also is there any relation between the acceleration of the two blocks