Smooth Pulleys and motion on an inclined plane

I have 3 questions.

1..A particle of mass 10kg is at rest on a plane inclined at an angle Tan-1 3/4 to the horizontal.Contact is rough where http://upload.wikimedia.org/wikipedi...an_mem.svg.png(Mu)is equal to .25. It is connected by a string passing over a smooth,fixed pulley to a second particle of mass 20kg hanging freely.the system is released from rest.

Find (i)Acceleration

(ii)Tension in the string

(iii)Force on the pulley

2..Two particles of mass 3kg and 5kg are connected by string.The 3kg lies on a plane inclined at 30 degrees and http://upload.wikimedia.org/wikipedi...an_mem.svg.png(mu) is equal to 1/5.The string lies parallel to a sloped plane and passes over a smooth pulley so that the 5kg hangs freely from the edge.the system is released.

Find (i)Tension in the string

(ii)Velocity after .5 seconds

(iii)If the string breaks,find the distance the 3kg mass travels up the plane before stopping

And finally 3..A particle of weight W is placed on a rough inclined plane,the inclination of which exceeds the angle of friction.The least horizontal force required to prevent motion down the plane is W.The least horizontal force required to produce motion up the plane is W http://upload.wikimedia.org/math/7/d...05105317da.png(square root of 3).

Find (i) Inclination of the plane

(ii)Angle of friction

(iii)The least force required to maintain equilibrium

Any Help will be greatly appreciated!!