Answer
a). (1) Positive.
b). $14.7mJ$
Work Step by Step
a). The eraser will move in the direction of the frictional force, thus work done by this force is Positive.
b). Displacement $=0.1m$
Coefficient of friction $=0.15$
Work done $=F\times d=0.15mg\times d=0.15\times0.1\times9.8\times0.1=14.7mJ$
