# OCR G481 Definitions

Definitions of all important units/words needed in the OCR G481 exam.

- Created by: Matthew D'Souza
- Created on: 17-04-12 21:21

First 264 words of the document:

Physics Definitions - G481

Quantity

Quantity - A quantity is a Measure of something and its Unit

Scalar Quantity - Quantities that have only Magnitude, e.g. Mass, Temperature and

Volume

Vector Quantity - Quantities that have both Magnitude and Direction e.g. Velocity, Force

and Acceleration

Motion

Speed - The rate of change of distance e.g. 10ms-1

Velocity - The rate of change of displacement e.g. 10ms-1 North

Displacement The net distance moved in a particular direction

Acceleration - A measure of how quickly velocity changes

Work Done - The energy transferred when an object is moved through a distance by a

force

Joule The energy required to move a weight of 1N through a distance of 1m

Power The rate of Work Done (work/time)

Watt Unit for power - One joule per second

Newton -The force that causes a mass of 1Kg to have an acceleration of 1 metre per

second per second (1N = 1Kgms-2)

Free Fall - Downward movement caused only by gravity

Terminal Velocity - The constant speed that a freely falling object eventually reaches when

gravitational force = air resistance and therefore net acceleration is

0

Equilibrium - An object is in equilibrium when net rotational and translational forces

equal zero

Moment - Force x Perpendicular distance from a pivot

Principle of Moments - For a body in rotational equilibrium, the sum of Clockwise

Moments = the sum of Anti-clockwise Moments

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