# DDP Chapter 9

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# Links for the Ninth Chapter

This video shows the importance of momentum.

This video gives a conceptual discussion of impulse. He uses “t” instead of “delta_t.”

This video shows you the equations related to impulse and solves a problem.

This video shows discusses when the Law of Momentum Conservation applies.

This video shows two demonstrations of the Law of Momentum Conservation.

This video shows examples of recoil in rifles.

This video shows two carts moving with equal but opposite momenta. Notice what happens when they collide.

This video solves a problem using the Law of Momentum Conservation.

This video solves a different problem using the Law of Momentum Conservation.

This video shows a Newton’s Cradle in action.

This video discusses why the number of moving balls must be the same after each collision in a Newton’s Cradle.

This video shows a ballistic pendulum working.

This video shows you how to solve a ballistic pendulum problem. He cancels mass out when he is dealing with the pendulum and the bullet, but you don’t have to, since you know both masses. Also, you don’t need to deal with the angle.

This video shows you a demonstration of angular momentum. He uses the term “momentum of inertia,” which you don’t need to know. Just realize that when the sphere is large, r (in l=mvr) is large. When the sphere is small, r is small.

This video shows you how to solve a conservation of momentum problem. He uses H instead of L, and you don’t have to worry about the total velocity he calculates at the end. You just need to worry about v_theta.

Extra Practice Problems for Chapter 9
The solutions for these problems can be found here.