# Coefficient of friction

• Nov 15th 2008, 09:38 AM
gracey
Coefficient of friction
Body A lies on a rough horizontal table and is connected to freely hanging bodies B and C by light inextensible strings passing over smooth pulleys.
A is 5kg B is 3kg and C is 2kg. When the system is released from rest, the body B descends with an acceleration of 0.28. Find the coefficient of friction between body A and the table.

Any help is much appreciated thanks
• Nov 15th 2008, 11:08 AM
skeeter
Let $\displaystyle T_1$ = tension between mass A and B
$\displaystyle T_2$ = tension between mass B and C

forces acting on mass A ...

$\displaystyle F_{net} = m_A a$

$\displaystyle T_1 - f_k = m_A a$

*** $\displaystyle T_1 - \mu m_A g = m_A a$

forces acting on mass B ...

$\displaystyle F_{net} = m_B a$

*** $\displaystyle T_2 + m_B g - T_1 = m_B a$

forces acting on mass C ...

$\displaystyle F_{net} = m_C a$

*** $\displaystyle m_C g - T_2 = m_C a$

solve the system of equations (***) for $\displaystyle \mu$