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Investigating Forces & Motion
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Investigating Forces and Motion (1998)(Granada Learning).iso
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INI File
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1998-02-10
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498 lines
[general]
wordcount:72
[word1]
word:acceleration
def:\
The rate at which velocity changes. \
Acceleration \
has units metre per second per second (m/s▓).<p>
[word2]
word:atmosphere
def:\
The mixture of gases, mainly nitrogen and oxygen, \
which clings in a layer to the Earth's surface.<p>
[word3]
word:barometer
def:\
An instrument for measuring atmospheric pressure.<p>
[word4]
word:Boyle's law
def:\
A sample of gas obeys Boyle's \
law if its pressure multiplied by \
its volume is a constant at constant temperature. <I>PV</I> = \
constant.<p>
[word5]
word:brittle
def:\
In a tensile test a brittle material, for \
example glass, snaps almost as soon as its elastic limit is exceeded.<p>
[word6]
word:centre of gravity
def:\
The single point in a body through which its weight \
(the force of gravity acting on the body) can be considered to \
act.<p>
[word7]
word:centripetal acceleration
def:\
Acceleration towards the centre of a circle. The \
acceleration of an object moving at a constant speed in a circle \
is always centripetal.<p>
[word8]
word:centripetal force
def:\
The force directed towards the centre of a circle \
which is needed to produce centripetal \
force and maintain circular motion.<p>
[word9]
word:compressive
def:\
A combination of two or more forces is compressive \
if it squeezes or squashes the object on which it acts.<p>
[word10]
word:contact force
def:\
The force that prevents one object passing into another \
when they are in contact. Contact \
forces are produced by electrical repulsion between the atoms \
in the two objects.<p>
[word11]
word:displacement
def:\
Distance moved or measured in a given direction. \
Displacement is a vector quantity \
with direction as well as size.<p>
[word12]
word:ductile
def:\
In a tensile test , a ductile \
metal, for example copper, stretches permanently (plastically) \
when its elastic limit is exceeded. The more ductile it is, the \
further it stretches before it fractures.<p>
[word13]
word:drag
def:\
The force that opposes the motion of an object \
though a fluid such as air or water.<p>
[word14]
word:dynamic friction
def:\
The frictional forces that oppose the relative \
motion of two surfaces which are in the process of sliding over \
each other.<p>
[word15]
word:elastic
def:\
A material is elastic \
if it returns to its original length when the stretching force \
is removed. All materials are elastic for small loads.<p>
[word16]
word:elastic limit
def:\
The limit beyond which any further increase in load \
changes the shape of a material permanently.<p>
[word17]
word:elastic potential energy
def:\
The energy stored in, for example, a stretched spring \
or elastic rope.<p>
[word18]
word:elasticity
def:\
The ability of a material to be deformed by forces \
then return to its original shape when the forces are removed.<p>
[word19]
word:energy
def:\
The capacity to do work or bring about change.<p>
[word20]
word:equilibrium
def:\
An object is in equilibrium \
if the forces acting on it are exactly balanced.<p>
[word21]
word:force
def:\
A push or pull that tends to change the motion of \
a mass. Examples of forces include \
the forces of gravity, electricity and magnetism.<p>
[word22]
word:gas
def:\
The state of matter in which the atoms or molecules \
of a substance move around freely and independently of each other. \
Gases are thin, usually invisible, \
substances that expand to fill their containers.<p>
[word23]
word:gradient
def:\
A slope. The gradient \
of a straight line graph is calculated by dividing the increase \
in <I>y</I> (the variable plotted on the vertical axis) by the \
corresponding increase in <I>x</I> (the variable on the horizontal \
axis).<p>
[word24]
word:gravitational potential energy
def:\
The potential energy stored by a mass when it is \
acted on by the force of gravity. Lifting a mass <I>m</I> through \
height <I>h</I> on the Earth's surface increases its gravitational \
potential energy by <I>mgh. \
</I><p>
[word25]
word:gravity
def:\
The attractive force that acts between all objects \
with mass. The force of gravity gives objects their weight and \
holds the planets in their orbits around the Sun.<p>
[word26]
word:Hooke's law
def:\
A material obeys Hooke's \
law when, in a tensile test, the extension is proportional to \
the load.<p>
[word27]
word:hydraulics
def:\
Hydraulic systems use liquids such as oil \
or water to transmit forces from one place to another. For example, \
hydraulic car brakes.<p>
[word28]
word:impulse
def:\
The impulse of a force \
is the force multiplied by the time for which it acts. Impulse \
= <I>Ft</I> = change in momentum.<p>
[word29]
word:joule
def:\
A unit of energy. One joule \
is the energy transferred when a force of one newton moves by \
a distance of one metre in the direction of the force.<p>
[word30]
word:kilogram
def:\
A unit of mass. A standard bag of sugar has a mass \
of 1 kilogram.<p>
[word31]
word:kilometre
def:\
One thousand metres.<p>
[word32]
word:kinetic energy
def:\
The energy that a moving mass has by virtue of its \
motion. \
Kinetic energy = ½mv▓ .<p>
[word33]
word:liquid
def:\
The state of matter in which the atoms or molecules \
of a substance are in close contact but tumble freely over each \
other. Liquids do not have a fixed \
shape. They flow to take the shape of their container.<p>
[word34]
word:lubricant
def:\
A substance such as oil that reduces the friction \
between two surfaces.<p>
[word35]
word:magnitude
def:\
The size of a quantity such as a vector or a number, \
without reference to its direction or sign.<p>
[word36]
word:manometer
def:\
An instrument for measuring pressure which consists \
of a U shape tube partly filled with liquid.<p>
[word37]
word:mass
def:\
Mass can be thought of as the 'amount of \
matter in an object'. The mass of an object determines how rapidly \
it accelerates when it is acted on by a force, and the strength \
of its gravitational attraction to other objects.<p>
[word38]
word:metre
def:\
The unit of length.<p>
[word39]
word:micrometer
def:\
A measuring instrument for measuring very small lengths.<p>
[word40]
word:micrometre
def:\
One millionth of a metre.<p>
[word41]
word:moment of force
def:\
The turning effect of a force. Also known as torque. \
The moment of the force about a point \
is the product of the force, and the perpendicular distance from \
the point to the line along which the force acts.<p>
[word42]
word:momentum
def:\
The product of the mass and the velocity of a moving \
object. Momentum = mass x velocity.<p>
[word43]
word:newton
def:\
The unit of force. One newton \
is the force that gives a mass of one kilogram an acceleration \
of one metre per second per second.<p>
[word44]
word:orbit
def:\
The path of a satellite around a star or planet. \
Orbits are circular or elliptical (like \
stretched circles).<p>
[word45]
word:parabola
def:\
A particular mathematical curve. The path followed \
by a projectile is a parabola.<p>
[word46]
word:pascal
def:\
The unit of pressure. One pascal \
is equal to a pressure of one newton per square metre. 1 Pa = 1 \
N/m▓.<p>
[word47]
word:plastic
def:\
A material is plastic \
if its shape is changed permanently when it is stretched or deformed \
in some other way by forces. Materials such as polythene are called \
'plastics' because they can undergo considerable plastic changes \
in shape.<p>
[word48]
word:potential energy
def:\
The energy an object has by the virtue of forces \
(for example gravitational or electrical forces) acting on it \
or within it.<p>
[word49]
word:power
def:\
The rate at which work is done or energy is transferred. \
Power = energy transferred/time.<p>
[word50]
word:pressure
def:\
The pressure on a surface \
is the force per unit area acting perpendicular to the surface. \
<P> \
Pressure = force/area.<p>
[word51]
word:projectile
def:\
A projectile is an object, \
for example a golf ball, launched horizontally or at an angle \
to the horizontal. The acceleration due to gravity, which always \
points vertically downwards, makes the projectile follow a parabolic \
path or 'trajectory'.<p>
[word52]
word:reaction force
def:\
For every force there is an equal and opposite \
reaction force. The 'action' and the 'reaction' forces always \
act on different objects. The contact force which prevents one \
object passing through another when they are pushed together, \
is often described as a reaction force.<p>
[word53]
word:resultant
def:\
The resultant of two \
forces acting together is a single force that produces the same \
acceleration. The resultant is found by adding the forces together \
and taking proper account of their direction. For example the \
resultant of two equal but opposite forces is zero.<p>
[word54]
word:rubber
def:\
A natural material that can be stretched elastically \
to several times its unstretched length.<p>
[word55]
word:scalar
def:\
A quantity such as mass, or speed which has a size \
but does not have a direction.<p>
[word56]
word:seismograph
def:\
An instrument used to record the Earth's vibrations, \
especially those produced by earthquakes.<p>
[word57]
word:shearing
def:\
The action of a pair of equal and opposite forces \
acting on opposite sides of an object, making one side slip or \
slide relative to the other.<p>
[word58]
word:speed
def:\
The rate at which distance is travelled. Speed \
= distance/time.<p>
[word59]
word:static friction
def:\
The frictional forces that oppose the relative motion \
of two stationary surfaces which are just on the point of sliding \
over each other.<p>
[word60]
word:streamlining
def:\
Shaping a vehicle or other object so that air or \
water flows past it smoothly producing as little drag as possible.<p>
[word61]
word:strength
def:\
The maximum load that a material can support before \
it fractures.<p>
[word62]
word:tensile test
def:\
A test in which a material is stretched by a load \
and the resulting extension is measured. The results of the test \
are recorded as a graph of load against extension.<p>
[word63]
word:terminal velocity
def:\
The steady velocity with \
which an object falls, following its initial acceleration, through \
a fluid. Terminal velocity is reached when drag forces exactly \
balance the object's weight.<p>
[word64]
word:torque
def:\
The turning effect of a force. Also known as the \
moment of the force. The moment of the force about a point is \
the product of the force, and the perpendicular distance from \
the point to the line along which the force acts.<p>
[word65]
word:vector
def:\
A quantity such as velocity or force that has both \
size and direction.<p>
[word66]
word:velocity
def:\
Speed in a particular direction. Velocity \
is a vector quantity with direction as well as size. Can also \
be defined as the rate of change of displacement.<p>
[word67]
word:watt
def:\
The unit of power. One watt \
is equal to a rate of energy transfer of one joule per second.<p>
[word68]
word:weight
def:\
The force of gravity on a mass, particularly at the \
surface of the Earth (or any other planet). On the Earth weight \
= <I>mg</I>, where <I>g</I> is the acceleration due to gravity at the \
Earth's surface.<p>
[word69]
word:weightless
def:\
A mass is weightless \
when it is in space, distant from any other masses. Masses also \
behave as if they are weightless when they are in 'free-fall', \
for example, inside a spacecraft orbiting the Earth.<p>
[word70]
word:work
def:\
Work is done when a force moves through a \
distance in the direction of the force. For example, when you push \
a swing you do work which increases the energy of the swing. The \
unit of work is that of energy - joule.<p>
[word71]
word:work hardening
def:\
When a metal is deformed plastically it becomes \
harder and more liable to crack. For example you can work harden \
a wire paper clip by bending it to and fro.<p>
[word72]
word:yield point
def:\
The load in a tensile test at which a specimen 'yields' \
and begins to stretch permanently. <p>