AP Physics 1 / Unit 3: Work, Energy, and Power
3.2 Work
Notes
$$W=Fd\cos\theta$$
- Work is positive if force and displacement point the same way; negative if opposite.
- Work-energy theorem: $W_{net}=\Delta K$.
Practice
You push a box 5 m with 10 N in the direction it moves. Work:
$10\times5$.
Friction on a sliding box does:
Opposes motion.
A force perpendicular to displacement (like the normal force on flat ground) does:
$\cos90°=0$.
Ready for more? Take the Unit 3 test.