Why this chapter matters
Energy methods often solve complex motion problems more directly than force-by-force kinematics.
What you will learn
- Compute work done by constant forces using force, displacement, and angle.
- Apply conservation of mechanical energy when assumptions are valid.
- Interpret power as the rate of energy transfer in physical and engineering contexts.
Lessons in this chapter
- Work by constant forcesDetermine positive, negative, or zero work from force-displacement geometry.
- Kinetic and potential energyRelate speed and position changes to energy changes in a system.
- Conservation of energyUse system boundaries to include or exclude nonconservative work.
- Power and efficiencyAnalyze how quickly energy is transferred or transformed.
Study task
Model a roller coaster segment with given heights and one friction region. Compute speeds at key points and compare energy before and after the friction segment.
Chapter checkpoint
How much work is done by a 10 N force parallel to a 3.0 m displacement?
W = Fd cos(theta). Here theta = 0 deg, so W = (10)(3.0)(1) = 30 J.