A block of mass m_block = 1.2 kg is placed atop a cart of mass m_cart = 3.4 kg. An unknown external force is then applied to the cart only, causing the system to accelerate. The coefficient of kinetic friction m_k = 0.4 and the coefficient of static friction m_s = 0.78.

What is the maximum acceleration of the system such that the block does not slip?

Use gravity g = 9.81 m/s².

a_max = m/s²