Answer
(a) Negative.
(b) $3700N$
Work Step by Step
(a) The speed and hence the kinetic energy of the car is decreasing which means that the work done on the car is negative.
(b) We know that
$W=\frac{1}{2}mv_f^2-\frac{1}{2}mv_i^2$
This simplifies to:
$F=\frac{-\frac{1}{2}m(v_f^2-v_i^2)}{d}$
We plug in the known values to obtain:
$F=\frac{-\frac{1}{2}(1100)((12)^2-(19)^2)}{32}$
$F=3700N$
