Units

What are the units of work?

Joules (J), which are Newton-meters (N$\cdot$m).

What are the sign conventions for work?

Positive (+) work is done when the force and the direction of travel are similar (e.g. pulling a crate). Negative (-) work is done when the force and the direction of travel are opposite to each other (e.g. friction).

How is work calculated?

$$W = Fd\cos \theta$$ (65.2)

Where $W$ is the work in Newton-meters (N$\cdot$m), $F$ is the force applied to the object in Newtons (N), $d$ is the displacement of the object in meters (m), and $\theta$ is the angle between the applied force and the displacement in degrees ($^{o}$).