# G481 KEY WORDS

Flashcards by sophiewalkerrock, updated more than 1 year ago
 Created by sophiewalkerrock over 7 years ago
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### Description

A Level Physics Flashcards on G481 KEY WORDS , created by sophiewalkerrock on 12/23/2013.

## Resource summary

 Question Answer Acceleration The rate of change of an objects velocity. a=v/t Unit: ms-2 Average Speed Total distance travelled by an object divided by the total time taken. Braking distance The distance travelled by a vehicle from the moment when the brakes are applied until the vehicle comes to a stop. Brittle Describes a material that shows no plastic deformation and breaks just beyond its elastic limit. Centre of Gravity The point where the entire weight of an object appears to act. Components (of a vector) The magnitudes of a vector quantity in two perpendicular directions. Compressive A force that squeezes an object Density The mass per unit volume of a material. p=m/V Unit: kgm-3 Displacement The distance moved by an object in a particular direction(measured from a fixed starting point) Ductile Describes a material that can easily be drawn into wires (e.g. copper) Dynamics A study of motion involving force and mass. Efficiency The ratio of useful output energy to the total input energy for a device, expressed as a percentage. Efficiency= Useful output energy x100 Total input energy Elastic Describes a material which will return to its original shape once the forces are removed. Elastic Limit The value of stress beyond which an object will not return to its original dimensions. Elastic Potential Energy Energy stored in an extended or compressed material. Equations of motion Equilibrium An object in equilibrium is either at rest or travelling with a constant velocity because the net force on it is zero. Extension The change in the length of a material from its original length. Force Constant The ratio of force to extension for a spring or a wire. Unit: Nm-1 Gravitational Potential Energy Energy stored by an object by vitue of its position in the Earths gravitational field. Hooke's Law The extension produced in an object is proportional to the force producing it, provided the elastic limit is not exceeded. Inertia A measure of the mass of an object. A massive object has a large inertia. Instantaneous speed The speed of an object measured over a very short period of time. Kilo-watt hour The energy transferred by a 1kW device in a time of 1 hour. 1kWh= 3.6 kJ Kinematics A study of motion using quantities such as time, distance, displacement, speed, velocity and acceleration. Kinetic Energy Energy of an object due to its motion Mass A measure of the amount of matter within an object. Unit: Kilograms Moment The moment of a force about a point is the magnitude of the force, multiplied by the perpendicular distance of the point from the line of the force. Unit: Nm Newton The force that will give a 1kg mass an acceleration of 1ms-2 in the direction of the force. 1N = 1kgms-2 Plastic Deformation The deformation of a material past its elastic limit. Power The rate at which energy is transferred or the rate at which work is done. Unit: watt (W) Pressure The force acting normally per unit area of a surface. p=F/A Unit: Nm-2 or Pa Principal of Moments The sum of clockwise moments about a point is equal to the sum of anticlockwise moments about the same point. Projectile Any object thrown in the Earths gravitational field. Range The horizontal distance covered by an object. Resultant Force The net force acting on an object. Scalar Quantity A scalar quantity has magnitude but no direction. Speed The rate of change of the distance moved by an object. Speed = Distance/time Unit: ms-1 Stopping Distance The sum of the thinking distance and the braking distance Strain The extension per unit length produced by tensile or compressive forces. Strain= extension original length Stress The force acting per unit cross-sectional area. Stress= Force Cross-sectional area Unit: Nm-2 Tensile A term used to denote tension or pull Terminal velocity The constant velocity of an object travelling through a fluid. The net force of an object is zero. Thinking distance The distance travelled by a vehicle in a time equal to the reaction time of the driver. Torque The product of one of the forces of a couple and the perpendicular distance between them. Unit: Nm Ultimate Tensile Strength (UTS) The breaking stress of a material. UTS = Breaking force Cross-sectional area Uniform Acceleration Uniform Motion Acceleration that remains constant. Motion of an object travelling with a constant acceleration. Vector Addition Vector Triangle Using a drawing, often to scale, to find the resultant vector. A triangle drawn to determine the resultant of two vectors. Vector Quantity A vector quantity has both magnitude and direction. Velocity The rate of change of the displacement of an object. Velocity = Change in displacement time Unit: ms-1 Weight The force of an object caused by a gravitational field acting on its mass. Weight = mass x acceleration of free fall Unit: newtons (N) Work Done The product of the force and the distance moved by the force in the direction of travel. Young Modulus The ratio of stress to strain for a given material, resulting from tensile forces, provided Hooke's law is obeyed. Young modulus=Stress/strain Unit: Pa

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