Final Answer:
(a) The angular acceleration of the arm is approximately

(b) The force required of the triceps muscle is approximately

Step-by-step explanation:
(a) The angular acceleration
can be calculated using the formula
, where
is the change in angular velocity and
is the change in time. In this case, the ball is released, so the angular velocity
becomes
at the end. The initial angular velocity is
because the ball starts from rest. Therefore,
Plugging in the values,
, which gives
.
(b) The force required
can be found using the equation
, where
is the torque,
is the moment of inertia, and
is the angular acceleration. The moment of inertia for a uniform rod rotating about its end is
where
is the mass and
is the length. The torque can be expressed as
, where
is the length from the axis to the point where the force is applied. In this case,
. Substituting these into the torque equation, we get
Plugging in the values,
, which simplifies to

In summary, (a) the angular acceleration of the arm is approximately
, and (b) the force required of the triceps muscle is approximately
