Essential Physics

Chapter study guide

Why do cars have crumple zones and airbags? How does rocket propulsion work? How can you predict where two pool balls will go after they collide? These are problems that involve momentum, impulse, and the conservation of momentum. Momentum is a physical description of mass in motion; the higher the mass or velocity of an object, the more momentum it has. The conservation of momentum is a fundamental law of physics—akin to energy conservation—that is essential for understanding collisions, whether between two cars or between two subatomic particles.

By the end of this chapter you should be able to
	describe momentum and impulse and solve problems using them;
	apply impulse to real-world problems, including situations involving cushioning and impacts;
	define momentum conservation and describe applications of it;
	use momentum conservation to solve noncollision problems;
	distinguish among elastic, inelastic, and perfectly inelastic collisions;
	apply momentum conservation to solve collision problems; and
	determine whether a collision is elastic using energy arguments.

Design project: Egg drop
11A: Conservation of momentum
11B: Collisions

306	Momentum and impulse
307	Momentum and inertia
308	Impulse and Newton’s second law
309	Impulse and momentum
310	Design an egg drop container
311	Impact forces and cushioning
312	Section 1 review
313	Conservation of momentum
314	11A: Conservation of momentum
315	Solving momentum conservation problems
316	Rocket propulsion
317	Section 2 review
318	Collisions
319	Inelastic collisions
320	11B: Collisions
321	Elastic collisions
322	Newton’s cradle
323	Collisions in two dimensions
324	Section 3 review
325	Chapter review

\vec{p} = m \vec{v}

J = Δ p = F Δ t

m_{1} v_{i 1} + m_{2} v_{i 2} = m_{1} v_{f 1} + m_{2} v_{f 2}

\frac{1}{2} m_{1} v_{_{i 1}}^{2} + \frac{1}{2} m_{2} v_{_{i 2}}^{2} = \frac{1}{2} m_{1} v_{_{f 1}}^{2} + \frac{1}{2} m_{2} v_{_{f 2}}^{2}

momentum	impulse	law of conservation of momentum
collision	inelastic collision	elastic collision


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