Question

when the work done by a force is negative this means that:

Answer 1

work done is either positive or negative

its depends on displacement .

if the force is done with the positive displacement then workdone by the force is positive. And if the force is done with negative displacement then workdone by the force is negative.

for example if one object is moving in the positive x direction then workdone is positive but frictional force is acting in opposite to the object moving ...... Hence workdone by the frictional force is negative workdone