【文章內(nèi)容簡介】 er at standard atmospheric pressure.Ideal gas: a hypothetical gas made up of a large number of small molecules that moves randomly and collides elastically with each other and obeys the ideal gas laws.Ideal gas law: an equation that describes the state of an ideal gas and has the following form: where p = pressure of the gas。 n = number of moles。 V = volume of the gas。 R = molar gas constant；T = temperature of the gas in kelvins.Impulse: the product of the force () acting on a body and the time interval (⊿t) over which the force acts.Inelastic collision: a collision in which linear momentum is conserved but kinetic energy is not conserved,Inertia: a measure of the resistance to changes in motion of a body.Infrared: an electromagnetic wave of wavelength to m in the electromagnetic spectrum. Insulator (electrical): a material that do not allow electric charges to flow through easily.Instantaneous acceleration: acceleration at a particular time. Instantaneous velocity: velocity at a particular time.Intensity (of a wave): the rate of How of energy per unit area perpendicular to the direction of the wave.Internal energy (of a thcrmodynamic system): the sum total of the kinetic and potential energies of all atoms and molecules in that system.Interference: the superposition of two or more wavetrains from coherent sources to form a new wave pattern.Joule: the work done when a force of one newton moves its point of application a distance of one metre in the direction of the applied force. It has the SI unit of newton metre.Kelvin: the fraction 1/ of the temperature difference between absolute zero and the triple point of water. It is the SI unit of thermodynamic temperature.Kilo: the prefix used to indicate the multiple of 103 of any units. It has the symbol of k.Kinematics: a branch of mechanics that describes the motion of a particle without reference to the force or energy that causes the motion.Kinetic energy: the energy possessed by a mass due to its motion. It is a scalar quantity.Kinetic theory of gases: A theory describing the physical properties of gases through the application of Newton39。s laws of motion on colliding gas molecules and offers an explanation on why gases obey the gas laws.Lift: the upward force exerted on an aeroplane caused by air flowing over the upper and lower wings of a moving plane at different speeds.Limit of proportionality: the point on a stressstrain curve at which the line changes from being linear (straight line) to nonlinear (a curve).Linear momentum (of a body): the product of mass and velocity of the bodyLiquid: a fluid in which molecules are not bounded in a rigid structure but each molecule is free to move through the body of the fluid and still maintain close proximity with other neighbouring molecules.Longitudinal waves: progressive waves in which the direction of vibrations of particles in the wave is along the line of flow of energyManometer: a mercuryfilled Utube that is used to measure the pressure difference of a fluid.Mass: a measure of a body39。s resistance to changes in motion. It is a base quantity with the, SI unit of kilogram.Mean square speed: the average value of the square of the molecular speeds.Measurement: the parison of a physical quantity with a calibrated measuring instrument in order to associate that physical quantity with a magnitude.Measurement error: see experimental error.Microwaves: electromagnetic waves with wavelengths that range from about 1 mm to about 10cm.Molar mass: the mass of one mole of a substance.Mole: the SI base unit for the amount of substance.Moment of a force (about a point): the product of the force and the perpendicular distance from the line of action of the force to the point.Newton: the force which produces an acceleration of 1 ms when it is applied to a mass of one kilogram.Newton39。s first law of motion: an object at rest will remain at rest and an object in motion will continue in motion at constant speed in a straight line in the absence of a resultant force.Newton39。s second law of motion: the rate of change of momentum of an object is directly proportional to the resultant force acting on that object and has the same direction as the force.Newton39。s third law of motion: action and reaction are always equal but oppositely directed on two different bodies.Newton39。s law of gravitation: a point mass will attract another point mass in any part of the universe with a force that is directly proportional to the product of the masses and inversely proportional to the square of the distance between them.Node: a point on a stationary wave where the amplitude of oscillation is zero.Parallax error: arises when the eye is not positioned vertically above the scale to be measured.Parallelogram law of vector addition: the resultant of two vectors acting at a point P is represented by the diagonal of a parallelogram formed by the two vectors and its origin is at F.Path difference: the extra length travelled by a wave when it is pared with another.Period: the time taken to generate a plete wave or to plete one oscillation of a vibrating system.Phase (of a particular point in an oscillation): the fraction of the oscillation measured from an initial chosen point and expressed in degrees (176。) or radians (rad).Phase difference: a measure of the extent to which a wave is out of phase with a reference wave and expressed in degrees (176。) or radians (rad). Physical quantities: quantities that are measurable and can be expressed as a numerical value and an acceptable standard or unit.Pitch: the frequency of a sound wave.Plastic deformation: the permanent change In structure of a material and the corresponding drastic change in shape and size when the material is subject to stress that is close to its breaking value,Potential energy in a system: the energy stored by virtue of its positio