1.1. A box $B$ of mass 5 kg rests on a rough horizontal table.  It is connected by a light inextensible string to a metal sphere $A$ of mass 2 kg.  The string passes over a smooth light fixed pulley at the edge of the table so that $A$ is hanging vertically downwards as shown in the diagram below:

The string between $B$ and the pulley is horizontal, and the magnitude of the frictional force between $B$ and the table is 15.1N.

The system is released from rest with the string taut and sphere $A$ begins to descend.

Let $T$ be the tension in the string after the particles are released, let $g$ be the constant of acceleration due to gravity, and let $a$ be the acceleration experienced by the particles (downwards in the case of $A$ and to the right in the case of $B$).  By considering the forces on each of the particles separately, use Newton’s Second Law of Motion to show that the following pair of simultaneous equations must be satisfied:

$2g-T=2aandT-15.1=5a$

1.2. By solving the simultaneous equations in part (a), determine the values of $a$ and $T$.