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## Homework Statement

Figure P8.36 shows a block of mass m resting on a 20° slope. The block has coefficients of friction µs = 0.83 and µk = 0.47 with the surface. It is connected via a massless string over a massless, frictionless pulley to a hanging block of mass m2 = 2.0 kg.

http://img6.imageshack.us/img6/9688/p836.gif [Broken]

(a) What is the minimum mass m that will stick and not slip?

**m_1=1.783kg**

(b) If this mimimum mass is nudged ever so slightly, it will start being pulled up the incline. What acceleration will it have?

**a_x= ???**

## Homework Equations

F=ma

T=ma

f_k=μ_k*n

n=m*g*cos(θ)

m_1 = 1.783kg

m_2 = 2.0kg

θ = 20 degrees

T = 19.6N

μ_k = 0.47

μ_s = 0.83

## The Attempt at a Solution

I found the mass m_1 using..

**(part A)**

**m_1=(T/(μ_s*g*cos(θ)+gsin(θ))**

..and I tried to find the a_x using forces..

**(Part B begins here)**

**T - f_k - m*g*sin(θ) = m*a_x**

..which gave me the equation...

**a_x=(T/m_1)-(μ*g*cos(θ))-(g*sin(θ))**

..and I am not sure if I am doing the math wrong but my answers are rejected.

Could anyone perhaps check my force diagram and algebra?

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