An overnight rainstorm has caused a major roadblock. Three massive rocks of mass $m_1=528kg,m_2=838kg,$ and

$m_3=344kg$ have blocked a busy road. The rocks are lined up from left to right in the order $m_1,m_2,$ and $m_3.$ The city calls a

local contractor to use a bulldozer to clear the road. The bulldozer applies a constant force to $m_1$ in order to slide the rocks off

the road.

Assuming the road is a flat, frictionless surface and the rocks

are all in contact, what force, $F_A,$ must be applied to $m_1$ to

slowly accelerate the group of rocks from the road at

$F_A=$

$0\mathrm{.}400\frac{m}{s^2}?$

Use the value for $F_A$ to find the force, $F_{12},$ exerted by $m_1$ on

$m_2$

$F_{12}=$