__Chapter Objectives and Summaries__

### for the Oxford University Press text by Walding, Rapkins and Rossiter:-

*" NEW CENTURY Senior Physics - Knowledge, Processes and Reasoning "*

### 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 = p
_{f}-p_{i}).
- 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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