Simple Note Physics Form 4

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PHYSICS FORM 4

TERMS AND DEFINITION

CHAPTER 1: INTRODUCTION TO PHYSICS

Physical quantities	QUANTITIES that are measurable
Base quantities	PHYSICAL QUANTITIES that cannot be defined in terms of other physical quantities but has its own definition
Derived quantities	PHYSICAL QUANTITIES that are derived from base quantities by multiplication or division or both
Scientific notation/standard form	POWERS of the base number 10 to show a very large or small number
Prefixes	GROUP OF LETTERS placed at the beginning of a word to modify its meaning, which act as multipliers
Scalar quantity	QUANTITY which has only magnitude or size(time, temperature, mass, volume, distance, density, power)
Vector quantity	QUANTITY which has both magnitude or size and direction(force, velocity, displacement, acceleration, momentum)
Error	DIFFERENCE between actual value of a quantity and the value obtained in measurement
Systematic errors	CUMULATIVE ERRORS that can be corrected, if the errors are known.(zero error, incorrect calibration of measuring instrument)
Random errors	ERRORS that arise from unknown and unpredictable variations in condition, and will produce a different error every time. Random errors are caused by factors that are beyond the control of observers.(human limitations, lack of sensitivity, natural errors, wrong technique)
Zero Errors	ERROR that arises when the measuring instrument does not start from exactly zero
Parallax error	ERROR in reading an instrument because the observer’s eyes and the pointer are not in a line perpendicular to the plane of scale
Measurement	PROCESS of determining value of a quantity using a scientific instrument with a standard scale
Consistency	ABILITY to register the same reading when a measurement is repeated(improve – eliminates parallax error, greater care, not detective instrument)
Accuracy	DEGREE to which a measurement represents the actual value(improve – repeat readings, avoid parallax/zero error, high accuracy instrument)
Sensitivity	ABILITY to detect quickly a small change in the value of a measurement(thermometer – thin wall bulb, narrow capillary)
Inferences	EARLY CONCLUSION that you draw from an observation or event using information that you already have on it
Hypothesis	GENERAL STATEMENT that is assumed to be true regarding the relationship between the manipulated variable and responding variable

CHAPTER 2: FORCES AND MOTION

Distance	how far a body travels during motion
Displacement	CHANGE IN POSITION of an object from its initial position in a specified direction
Speed	RATE OF CHANGE of distance
Velocity	RATE OF CHANGE of displacement
Mass	MEASURE of an object’s inertia /AMOUNT of matter in the object
Acceleration	RATE OF CHANGE of velocity
Inertia	PROPERTY of matter that causes it to resist any change in its motion or state of rest
Momentum	PRODUCT of mass and velocity
Force	pulling or a pushing ACTION on an object
Impulsive force	LARGE FORCE which acts over a very short time interval / RATE OF CHANGE in momentum
Gravity	FORCE originated from centre of the Earth that pulls all objects towards the ground
Free fall	FALLING of an object without encountering any resistance from a height towards the earth with an acceleration due to gravity
Forces inequilibrium	An object is said to be in a state of equilibrium when forces act upon an object and it remains stationary or moves at a constant velocity
Resultant force	SINGLE FORCE which combines two or more forces which act on an object
Work	Work is done when a force causes an object to move in the direction of the force.
Energy	CAPACITY of a system to do work
Gravitational PE	ENERGY STORED in the object because of its height above the earth surface
Elastic PE	ENERGY STORED in the object as a result of stretching or compressing it
Kinetic energy	ENERGY possessed by a moving object
Power	RATE at which work is done or energy is changed and transferred
Efficiency	ABILITY of an electrical appliance to transform energy from one form to another without producing useless energy or wastage
Elasticity	PROPERTY of an object that enables it to return to its original shape and dimensions after an applied force is removed
Spring constant	FORCE needed to extend a spring per unit length
Elastic limit	MAXIMUM STRETCHING FORCE which can be applied to an elastic material before it ceases to be elastic

PRINCIPLE

Hooke’s Law	Hooke’s law states that the force, F applied to a spring is directly proportional to the spring’s extension or compression, x, provided the elastic limit is not exceeded
Principle of conservation of energy	Principle of conservation of energy states that total energy in an isolated system is neither increased nor decreased by any transformation. Energy cannot be created nor destroyed, but it can be transformed from one kind to another, and the total amount stays the same.
Principle of conservation of momentum	The principle of conservation of momentum states that, in any collision or interaction between two or more objects in an isolated system, the total momentum of the system will remain constant; that is, the total initial momentum will equal the total final momentum.
Newton’s first law of motion	Newton’s first law of motion states that a body will either remain at rest or continue with constant velocity unless it is acted on by an external unbalanced force.
Newton’s second law of motion	Newton’s second law of motion states that the acceleration a body experiences is directly proportional to the net force acting on it, and inversely proportional to its mass. F =ma
Newton’s third law of motion	Newton’s third law of motion states that to every action there is an equal but opposite reaction.

CHAPTER 3: FORCES AND PRESSURE

Pressure	FORCE acting normally on a unit surface area
Gas pressure	FORCE per unit area exerted by the gas particles as they collide with the walls of their container (due to the rate of change of momentum)
Buoyant force	NET FORCE acting upwards due to the difference between the forces acting on the upper surface and the lower surface

PRINCILPE

Law of Flotation	Law of floatation states that the weight of an object floating on the surface of a liquid is equal to the weight of water displaced by the object.(weight of object = weight of water displaced)
Pascal’s Principle	Pascal’s principle states that a pressure applied to a confined fluid is transmitted uniformly in all directions throughout the fluid.
Archimedes’ principle	Archimedes’ principle states that the buoyant force on a body immersed in a fluid is equal to the weight of the fluid displaced by that object(buoyant force = weight of water displaced)
Bernoulli’s principle	Bernoulli’s principle states that the pressure of a moving fluid decreases as the speed of the fluid increases, and the converse is also true

CHAPTER 4: HEAT

Temperature	DEGREE of hotness of an object
Thermometric property	PHYSICAL PROPERTY of a substance which is sensitive to and varies linearly with the temperature change
Thermal equilibrium	A STATE when heat transfer between the two objects are equal and the net rate of heat transfer between the two objects are zero
Heat capacity	HEAT ENERGY required to raise its temperature by 1°C or 1 K
Specific heat capacity	HEAT ENERGY required to produce 1°C or 1 K rise in temperature in a mass of 1 kg.
Latent heat	HEAT ABSORBED OR RELEASED when a substance changes its state without a change in temperature is called the latent heat of the substance.
Specific latent heat of fusion	HEAT ENERGY required to change 1 kg of a substance from solid state to liquid state, without a change in temperature
Specific latent heat of vapourisation	HEAT ENERGY required to change 1 kg of a substance from liquid state to gaseous state, without a change in temperature

PRINCIPLE

Boyle’s Law	Boyle’s Law states that the pressure of a fixed mass of gas is inversely proportional to its volume provided the temperature of the gas is kept constant(PV = k)
Pressure Law	The pressure law states that the pressure of a fixed mass of gas is directly proportional to its absolute temperature (in Kelvin), provided the volume of the gas is kept constant(P/T = k)
Charles’ Law	Charles’ law states that the volume of a fixed mass of gas is directly proportional to its absolute temperature (in Kelvin), provided the pressure of the gas is kept constant(V/T = k)

CHAPTER 5: LIGHT

Refraction	PHENOMENON where the direction of light is changed when it crosses the boundary between two materials of different optical densities as a result of a change in the velocity of light.
Apparent depth, d	DISTANCE of the image from the surface of water (or the boundary between the two mediums involved)
Real depth, D	DISTANCE of the object from the surface of the water (or the boundary between the two mediums involved)
Total internal reflection	TOTAL REFLECTION of a beam of light at the boundary of two mediums, when the angle of incidence in the optically denser medium exceeds a specific critical angle
Critical angle	GREATEST ANGLE OF INCIDENCE in the optically denser medium for which the angle of refraction, r = 90°
Power of lens	MEASURE OF ITS ABILITY to converge or diverge an incident beam of light

PRINCIPLE

Laws of Reflection	§  the angle of incidence, i, is equal to the angle of reflection, r (i = r) §  the incident ray, normal and reflected ray will all lie in the same plane
Law of Refraction	§  The incident ray and the refracted ray are on the opposite sides of the normal at the point of incidence, all three lie in the same plane §  Obey Snell’s law
Snell’s Law	The value of   sin i / sin r is a constant.

IMAGE CHARACTERISTICS

Virtual - an image which cannot be projected (focused) onto a screen

Real - an image which can be projected (focused) onto a screen

Laterally inverted - an image which left and right are interchanged

Upright - an image which in vertical position

Diminished - image formed is smaller than the object

Magnified - image formed is larger than the object

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