Definitions Flashcards
MASS
The quantity of matter contained within a body.
Symbol: m
Unit: kg
WEIGHT
The force of attraction of gravity on a given mass.
Formula: W = mg
Unit: Newton
DISTANCE
The interval between 2 points, not in a straight line.
Symbol: d
SI Unit: metre (m)
DISPLACEMENT
The linear distance between 2 defined points.
Symbol: s
SI Unit: metre (m)
SCALAR
Sufficiently defined when magnitude only is given in the appropriate units.
E.g. distance
VECTOR
Requires direction to be stated in order to completely define it.
E.g. velocity - as it has magnitude.
Direction - metres per a second.
SPEED
The rate of change of distance with time.
Symbol: U & V
Units: m/s
VELOCITY
The rate of change of displacement with time. (Speed with a specific direction is a velocity)
Symbol: U & V
Units: m/s
ACCELERATION
The rate of change of velocity with time.
Symbol: a
SI Units: m/s^2
FORCE
An external agency capable of altering the state of rest or uniform motion of a body.
The force , F, required to produce an acceleration, a, in a mass, m, is given by: F=ma
Symbol: N
SI Unit: Newton
NEWTON
The force requires to give a mass of 1 kilogram an acceleration of 1 metre per a second.
A Newton is a unit of force, reoriented by the symbol N.
CENTRIPETAL ACCELERATION
The acceleration of a body travelling in a curved path that is directed towards the centre of the curve or axis of rotation.
The magnitude of centripetal acceleration is given by the equation: a= v^2 / r
CENTRIPETAL FORCE
The external force required to make a body follow a curved path.
The magnitude of the centripetal force is given by the equation:
Fc = mv^2 / r
CRITICAL SPEED
The maximum speed in which a body can travel in a curved as limited by the centripetal acceleration.
GRAVITATIONAL FORCE
The force of attraction between all objects that tends to pull them towards one another.
Symbol: g
Units: m/s^2
Value: 9.81 m/s^2
CENTRE OF GRAVITY
The fixed point through which the resultant force of gravity always passes, irrespective of the position of the body.
INERTIA
The property of matter that causes it to resist any change of its motion in either direction or speed.
FRICTION
The force that opposes the relative motion or tendency to such motion of 2 surfaces in contact.
COEFFICIENT OF SLIDING FRICTION
The ratio between the force required to keep a body in uniform motion over a surface and the weight of that body.
Represented by μ (mu)
μ = force / weight
DYNAMICS
The branch of mechanics concerned with the motion of bodies under the attraction of force.
MOMENTUM
The momentum of an object is defined as the product of a mass and its velocity.
Symbol: p
Equation: p = mv
INERTIAL FRAME OF REFERENCE
A frame of reference that is not accelerating or rotating.
NEWTONS 1st LAW OF MOTION
A body in motion remains in motion or a body in rest remains at rest, unless acted on by another force.
NEWTONS 2nd LAW OF MOTION
The rate of change of momentum is proportional to the applied force and takes place on the direction of the applied force.
Force equals mass times acceleration.
F = ma
NEWTONS 3rd LAW OF MOTION
For every action, there is an equal and opposite reaction.
