Topic 3.2: Work

Name: _______________________________ Date: _______________ Period: _______

Key Ideas

• Work: $W=Fd\cos\theta$, where $\theta$ is the angle between the force and the displacement. Units: joules (J).
• Only the force component parallel to displacement does work; a force exactly perpendicular to displacement (like tension in circular motion) always does zero work.
• $\theta<90°\Rightarrow W>0$; $\theta>90°\Rightarrow W<0$; $\theta=90°\Rightarrow W=0$. Total work from multiple forces = the sum of each force's individual work.
• For a variable force, $W=$ area under a Force-vs-Position graph — break irregular shapes into triangles, rectangles, or trapezoids and add.
• The work-energy theorem: $W_{net}=\Delta K$ — net work is nonzero only when kinetic energy is actually changing.

Keep This Sheet!

These sheets build into your semester study guide. Keep them in order in a binder or folder — you'll want to flip back through them before quizzes, unit tests, and when AP exam review starts in the spring.