## Chapter Objectives and Summaries

### CHAPTER 8 Momentum

LEARNING OBJECTIVES
Knowledge of subject matter
• Define centre of mass, momentum and impulse.
• Calculate the momentum of an object (p = mv).
• Calculate the impulse given to an object( Ft = pf-pi).
• State the law of conservation of momentum and use it to solve simple problems.
• Relate Newton's third law of motion to momentum.
• Describe everyday situations that involve changes in momentum.
• Describe the notion of conservation of angular momentum in terms of everyday phenomena.

SCIENTIFIC PROCESSES

• Discuss reasons why various safety features are built into modern motor vehicles.
• Analyse data from collisions and explosions in one dimension.

COMPLEX REASONING PROCESSES

• Apply momentum and impulse principles to car accident analysis.
• Calculate the motion of the centre of mass of a two object isolated system.
• Calculate the motion of objects undergoing collisions and explosions in two dimensions.

### CHAPTER 8 SUMMARY

• The centre of mass is a point at which the mass of a system of particles can be considered to act.
• The product of mass and velocity is the vector quantity called momentum: p = mv. The direction of momentum is the same as the direction of velocity.
• The product Ft is called the impulse.
• The area under an F/t graph is the impulse and is measured in newton second (N s).
• The Law of Conservation of Momentum states that for a closed, isolated system, the momentum before an interaction equals the momentum afterwards.
• Momentum is conserved in explosions and collisions in linear, two dimensional and three dimensional interactions.
• Collisions can be thought of as being the rebound type or the coupled type.
• Collisions can be analysed using vector processes.

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