# Physics nptes key definitions. Newtons Law And Momentum, Circular Motion And Oscillations, Thermal Physics

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Introduction

Physics Unit 1: The Newtonian World

## Module 1: Newton’s Law And Momentum

- Newton’s First Law – A force is necessary to change the state of rest or of uniform motion in a straight line of a body
- Momentum/Linear Momentum – The mass of an object multiplied by its velocity
- Newton’s Second Law – The rate of change of the momentum of an object is directly proportional to the resultant net force acting upon it
- One Newton is the force that gives a mass of one kilogram an acceleration of one metre per second each second
- Mass – The inertia of an object/how difficult it is to accelerate an object

Middle

## Module 2: Circular Motion And Oscillations

- Radian – The angle subtended at the centre of a circle by an arc of length equal to the circle’s radius
- Period – The time taken to complete one revolution
- Centripetal Acceleration – The acceleration of a body moving in a circle with a constant speed
- Field – The region in which a force operates
- Gravitational Field Strength – The force acting per unit mass at that point
- Newton’s Law Of Gravitation – The gravitational force of attraction between two bodies is directly proportional to the product of their masses and inversely proportional to the square of the distance between them

Conclusion

- Phase – Whether a substance is a solid, liquid or a gas
- Internal Energy – The sum of the random distributions of kinetic and potential energies of all the molecules in the body
- Ideal Gas – A gas that has internal energy only in the form of random kinetic energy
- Thermal Equilibrium – Two objects at the same temperature
- Specific Heat Capacity – The quantity of thermal energy required to raise the temperature of a unit mass of a substance by a unit temperature rise
- Specific Latent Heat – The quantity of energy per unit mass required to change it at constant temperature from a solid into a liquid
- Boyle’s Law – The volume of a fixed mass of gas is inversely proportional to the pressure exerted on it, provided the temperature is kept constant

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## Here's what a star student thought of this essay

### Response to the question

The candidate has summarised key points that are relevant to this topic. They have managed to include most of the points outlined on the specification and for the most part the information provided is extremely accurate. This demonstrates a good ...

Read full review### Response to the question

The candidate has summarised key points that are relevant to this topic. They have managed to include most of the points outlined on the specification and for the most part the information provided is extremely accurate. This demonstrates a good understanding of underlining principles.

### Level of analysis

Generally the information that the candidate has stated is accurate, though there are a few errors. For example in the first section, when stating Newton’s second law of motion, the candidate has failed to mention that the change in momentum and the net force must be in the same direction. There is also key information missing, for example the candidate fails to mention that momentum is a vector quantity, which is essential when solving problems related to the momentum of given objects, if you fail to state the direction of the velocity of an object your calculations will be incorrect. In addition to this, the section on module three is relatively short and seems to be missing some important facts such as the concept of internal energy related to state changes, a description of Brownian motion and several other points. The candidate’s work could be improved with additional details and further development of key points, for example, when discussing the definitions used for an object demonstrating simple harmonic motion, it would be appropriate to provide graphs of displacement, velocity and energy as these need to be understood and can be tested on in examinations.

### Quality of writing

The candidate uses technical terms accurately and clearly demonstrates a good understanding of this topic. In addition the language used to describe key terms is of the standard I would expect from a grade A/B candidate. Furthermore there are no issues with spelling or grammar and the information is displayed in a clear and coherent manner.

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Reviewed by pictureperfect 26/06/2012

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