Answer
(a) $-10J$
(b) $0.63N$ upward
Work Step by Step
(a) We know that
$W=Delta K.E$
$W=K.E_f-K.E_i$
$W=\frac{1}{2}mv_f^2-mgh$
$W=m(\frac{1}{2}v_f^2-gh)$
We plug in the known values to obtain:
$W=(0.140)[\frac{1}{2}(13)^2-(9.81)(16)]$
$W=-10J$
(b) We know that
$W=-Fd$
This can be rearranged as:
$F=\frac{-W}{d}$
We plug in the known values to obtain:
$F=\frac{-(-10)}{16}$
$F=0.63N$ upward