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Mechanics Def'ns
MechanicsDefinitions
Term | Definition |
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Physical Quantity | A quantity that can be measured, or calculated, and expressed in numbers |
Scalar Quantity | A quantity with magnitude only, not direction |
Distance | A measure of how far one point is from another |
Displacement | An object's overall change in position |
Time | Used to measure the duration of an event or the interval between events |
Speed | Rate of change of distance with respect to time |
Vector Quantity | A quantity with both magnitude and direction |
Velocity | Rate of change of displacement with respect to time |
Acceleration | Rate of change of velocity with respect to time |
Mass | A measure of the amount of matter in a body |
Momentum | The product of mass and velocity |
Force | That which causes acceleration |
Acceleration due to gravity | The acceleration experienced by a body in free fall within the gravitational field of a massive body |
Weight | A force equal to the product of mass and acceleration due to gravity |
Centre of gravity | The point at which the whole weight of a body appears to act |
Friction | A force that opposes the motion of a body |
Moment of a Force | The force multiplied by the perpendicular distance to the fulcrum |
Lever | A rigid body that is free to rotate about a fixed axis |
Couple | A pair of equal and opposite forces whose lines of action do not coincide |
Torque of a Couple | Product of the magnitude of one of the forces and the distance between the two forces |
Density | Mass per unit volume |
Pressure | Force per unit area |
Buoyancy | Upward force on a body that is wholly or partly immersed in a fluid |
Work | Product of force and displacement |
Energy | Ability to do work |
Kinetic Energy | Energy a body has due to its motion |
Potential Energy | Energy a body has due to its position |
Power | Rate at which work is done |
Radian | A measure of angle found by dividing arc length by radius |
Angular Velocity | Rate of change of angle with respect to time |
Linear Velocity | Rate of change of displacement with respect to time in a direction perpendicular to the radius at that point |
Periodic Time | Time taken for one complete revolution, cycle or oscillation |
Centripetal Acceleration | Acceleration of an object travelling in uniform circular motion, directed towards the centre of the circle |
Centripetal Force | Force required to keep up uniform circular motion, directed towards the centre of the circle |
Elastic Constant | Constant of proportionality between force applied and the resulting displacement of spring/elastic string |
Elasticity | Ability of a body to resist a distorting influence or stress and to return to its original shape and size when the stress is removed |
Simple Harmonic Motion | When the acceleration of a body towards a particular point is proportional to displacement away from that point |
Amplitude | Maximum distance an object moves away from its equilibrium position |
Frequency | Number of revolutions, cycles or oscillations an object completes per unit time |
Period of SHM | Time taken for one complete revolution, cycle or oscillation |