Work done by the force in the various scenarios are explained here:
1. The work done by the force is positive when the force and the displacement are in the same direction (θ=00)
2. Work done by the force is negative when the force and the displacement are in opposite directions (θ=1800)
3. Work done by the force is zero when the applied force does not cause any displacement or when the force and the displacement are perpendicular to each other (θ=900)