Answer
(a) W = 40 J
(b) W = 20 J
(c) W = 60 J
Work Step by Step
To find the work done by the force, we need to calculate the area under the F versus x graph.
(a) $W = \frac{1}{2}(10~N)(8.0~m)$
$W = 40~J$
(b) $W = \frac{1}{2}(10~N)(4.0~m)$
$W = 20~J$
(c) $W_{tot} = 40~J + 20 ~J = 60~J$