
absolute zero 
Lowest possible temperature at which gas would have zero volume. 
absorbed dose 
Describes how much energy is deposited by a source per kilogram of exposed tissue. Its SI unit is the gray (Gy) and a common nonSI unit is Rads.
1 Gy = 1 J/kg = 100 Rads
The radiation for the treatment of cancer generally involves an absorbed dose of 40 Gy.

acceleration 
Change in velocity divided by time interval over which it occurred. 
activity 
Number of decays per second of a radioactive substance. 
air resistance 
Force of air on objects moving through it. 
alpha particle 
Positivelycharged particles consisting of two protons and two neutrons emitted by radioactive materials. Are positively charged particles emitted from alpha decay. These particles are helium nuclei. 
ammeter 
device to measure electrical current. 
annihilation 
Process in which a particle and its antiparticle are converted into energy. 
antenna 
Device used to receive or transmit electromagnetic waves. 
antineutrino 
Subatomic particle with no charge or mass emitted in beta decay. 
Applied Force () 
A push or a pull that is applied to an object. The unit for force is the Newton (N). It is a vector quantity and therefore requires direction. 
artificial radioactivity 
Radioactive isotope not found in nature. 
atomic mass unit (u) 
Unit of mass equal to 1/12 the atomic mass of the carbon12 nucleus. 
atomic number (Z) 
Number of protons in the nucleus of the atom. 
average acceleration 
Acceleration measured over a finite time interval. 
average speed 
Is the total distance traveled divided by the change in time. 
average velocity 
Velocity measured over a finite time interval. The slope of the line is a ratio of the rise to the run. The change y over the change over x. 

Base Level 
Is an arbitrary reference point from an object\'s vertical position may be calculated. This change in height relative to the reference point may then be used to calculate gravitational potential energy. 
becquerel (Bq) 
Measures the activity of a source. One becquerel is equal to one emission per second.
1 Bq = 1 emission per second = 1 Curie (Ci)

beta particles 
Are electrons that are emitted from beta decay. For an electron, the subscript represents the charge and not, as in most cases, the number of protons. 







Calandria 
This is another word for Reactor Vessel. It contains the pressure tubes and the moderator. 
CANDU reactor 
Canadian Deuterium Uranium Reactor is one of the safest fission reactors in the world. It was developed by members of the AECL (Atomic Energy of Canada Limited). 
Chain Reaction 
A nuclear reaction where the neutrons produced during a reaction causes a chain of similar reactions. A controlled chain reaction occurs in a nuclear reactor whereas in an atomic bomb an uncontrolled chain reaction occurs. 
Chassis Ground 
A chassis ground or a ground may be a common plane of zero voltage compared with the rest of the circuit. 
collinear vectors 
Are vectors that are in the same direction or the exact opposite direction. They exist in only one dimension. 
Condensers 
Change the steam in a nuclear reactor back into water so that it can be cycled back into the steam generator. 
constant acceleration 
occurs when the objects velocity changes by equal amounts in equal periods of time. 
constant speed 
occurs when the object travels the same distance in equal periods of time. The SI unit is the meter per second (m/s). 
constant velocity 
occurs occurs when the object has the same displacement in equal periods of time. 
Control Rods 
Are used to control the rate of a chain reaction by capturing neutrons. They are often made of boron or cadmium and are inserted into the moderator and fuel to reduce the rate of fission. 
Coolant 
The coolant used in the CANDU reactor is heavy water. It flows through the pressure tubes in the calandria and transfers the heat from the fuel to ordinary water through a heat exchanger. This ordinary water produces steam, which will turn turbines to generate electricity. 
Critical Mass 
Is the minimum mass of fissionable material that will produce a nuclear explosion. If the amount of U235 is to small, the neutrons produced during fission will be less than the number of neutrons that will escape from the surface of the mass.( i.e. no sustained chain reaction) 
Current 
is the rate of flow of charge passing through a crosssectional area in a conductor. It is considered to be a flow of positive charge. 

dependent variable 
A mathematical variable whose value is determined by the value assumed by an independent variable. This value is plotted on the yaxis. 
Deuterium 
Is an isotope of hydrogen that has one neutron in the nucleus,. 
displacement () 
Is the change in position of an object. It is the straight line segment that connects the initial and final positions. Displacement is a vector quantity and therefore needs to be described with a magnitude and a direction. The SI unit is the meter. 
distance () 
Is the length of the path traveled by an object as it moves from one point to another. It is a scalar quantity and therefore only needs to be described using a magnitude. The SI unit is the meter. 
dose equivalent 
Measures the biological damage produced on an organism. Its SI unit is the sievert (Sv).
Dose equivalent (Sv) = absorbed dose (Gy) quality factor (Q).

dosimetry 
Is the measurement of radiation and the study of its effects on living organisms. 
Dot Interval 
The space between the dots on a recording tape. 
Dynamics 
The branch of physics that examines the description of motion and the forces behind the motion. 

Elastic Collision 
Is one in which there is no change in kinetic energy after the collision has occurred. Kinetic energy is conserved. 
Electric Field 
An electric field is a region in space where a force is exerted on a positive test charge. 
Electric Lines of Force 
Electric lines of force represent the direction that a positive test charge would move in an electric field. By convention, they originate at positively charged objects and terminate at negatively charged objects. 
Electric Potential Difference 
The electric potential difference (V) is the work done per unit charge as a charge is moved between two points in an electric field. 
Energy (E) 
Is the ability to do work. When work is done, energy is transferred from one object to another. The unit for energy is the Joule. 
Enrichment 
The process of increasing the percentage of uranium235 in a natural uranium ore so that a chain reaction will be sustained. 
Equivalent Displacements 
Are displacements that have the same magnitude and direction. Equivalent displacements do not need to have the same origin. 
Equivalent Vectors 
Are vectors with the same magnitude and direction. 
Equivalent (total) Resistance 
This resistance can be considered to consist of a single resistance, which replaces two or more resistances. 



Fission 
Results when a slow moving neutron is absorbed by a heavy nucleus causing it to split into smaller nuclei. 
force of gravity 
The force which is caused by the attraction between two objects due to their mass. 
Frequency (f) 
The number of vibrations per unit time. One vibration per second is called one hertz (Hz). 
friction force 
The force which acts between the surfaces of two objects in contact. 
Fuel bundles 
Contain cylindrical rods made up of uranium oxide fuel pellets. These fuel bundles are placed in special pressure tubes inside the calandria. 

Galileo's Thought Experiement 
Galileo developed the concept of inertia. 
Gamma rays 
Are usually emitted along with alpha and beta decay. Gamma rays are electromagnetic radiation ( a form of light) that produces no change in the atomic mass or atomic number of the radioactive nucleus. The symbol used for gamma rays is . 
Graphing 
A diagram that exhibits a relationship, often functional, between two sets of numbers as a set of points having coordinates determined by the relationship. 
Gravitational Potential Energy 
Is the energy stored as a result of the vertical position (height) of an object. It\'s position may be relative to the ground level or a base level. It may be calculated using E_{g} = mgh where E_{g} = gravitational potential energy (J) m = mass of the object (kg) g = 9.80 m/s^{2}h = change in height relative to the reference point (m) 
Ground Level 
Is the surface of the earth or the floor of any room from an object\'s vertical position may be calculated. This change in height relative to the reference point may then be used to calculate gravitational potential energy. 

Heavy water 
The chemical symbol for heavy water is D_{2}O. It contains deuterium which is an isotope of hydrogen. It is used as the moderator and the coolant in the CANDU reactor. 
horsepower 
One horsepower is equal to 746 joules/second (746 W). The unit horsepower was used to describe the output of a workhorse. 





independent variable 
A variable whose value determines the value of other variables (dependent variable). This value is plotted on the xaxis. 
Inelastic Collision 
Is one where some energy is "lost" when colliding objects are in contact. This "lost" or dissipated energy usually results in the production of heat. It may also produce sound, light, or other forms of energy. 
inertia 
a property of matter by which it remains at rest or in uniform motion in the same straight line unless acted upon by some external force. 
instantaneous acceleration 
is the acceleration of an object at a specific time. 
instantaneous speed 
is the speed at a specific instant in time. The SI unit is the meter per second (m/s). 
instantaneous velocity 
is the instantaneous speed in a specific direction. 
isotopes 
Are elements that have the same atomic number but different atomic masses due to a change in its number of neutrons. 








Kinematics 
The branch of physics that involves the description of motion without examining the forces which produce the motion. 
Kinetic Energy 
Is the energy of motion. It can be calculated by where: E_{k} = kinetic energy (J) m = mass (kg) v = velocity or speed (m/s) 
Gustav Robert Kirchhoff 
Born: 12 March 1824 in Königsberg, Prussia (now Kaliningrad, Russia) Died: 17 Oct 1887 in Berlin, GermanyKirchhoff's laws, which he announced in 1845, allowed calculation of currents, voltages and resistances in electrical circuits with multiple loops, extending the work of Ohm. Kirchhoff considered an electrical network consisting of circuits joined at nodes of the network and gave laws which reduce the calculation of the currents in each loop to the solution of algebraic equations.

Kirchhoff's Current Law 
At any junction in an electric circuit, the total current flowing into the junction is the same as the total current leaving the junction. 
Kirchhoff's Voltage Law 
The algebraic sum of the potential difference around any closed path or loop must be zero. 








Moderator 
Is a substance that is used to slow down the neutrons in nuclear reactors. Some common moderators are: graphite, heavy water, and beryllium. 
motion 






Negative work 
Is done when the applied force and the displacement act in opposite directions. 
noncollinear vectors 
Are vectors that exist in more than one dimension. 
nonuniform motion 
Is motion where the direction and/or the speed of the object can change. Nonuniform motion has a change in velocity which has a special name called acceleration. 
normal force 
The force which acts perpendicular to the plane at which the object rests. 
Nuclear Fuel Cycle 
The entire cycle from mining the fuel to its disposal after use. 
Nuclear Mass Defect 
Is the difference between the masses of the parent atom and the slow moving neutron and the masses of the daughter atoms with the emitted neutrons. It can be used to determine the energy released during fission.
where E = energy released
c = speed of light =
m= nuclear mass defect

Nuclear Reactor 
It is a device where a controlled chain reaction occurs. The energy released from this reaction is used to drive turbines, which generate electricity. 








Parallel Circuit 
In this circuit, electrons can flow along one or more pathways (i.e. alternate paths for current to follow). 
period (T) 
Is the length of time required for one vibration. A period is usually expressed in seconds. 
physical quantity 
A quantity that can be measured. 
Physics 
The branch of science that studies the physical world. 
power 
Is the rate at which work is done. It is a scalar quantity with SI units of watts (W). Another commonly used unit is the horsepower.
Since work done is approximately equal to the energy used, W = ~E, power can also be described as the rate at which energy is used. 
position () 
The location of an object relative to a reference point. It is a vector quantity and as such needs a magnitude and direction. The SI unit is the meter. 
Positive work 
Is done when the applied force and the displacement act in the same direction. 
Potential Energy 
energy of rest. 

Quality factor 
A number assigned to each type of radiation to describe its biological effects. It was defined by comparing its effects with those of a standard radiation of 200 keV Xrays. Quality factors are approximate since they depend on the energy of the radiation and the type of tissue being irradiated.
Note: a keV is a kiloelectronvolt






radioactivity 
Is the spontaneous breakdown of an atom and results in the emission of particles or electromagnetic radiation. 
reference point 
Is the zero or initial location of an object. 
Resistance 
Resistance is anything that causes an opposition to the flow of electricity in a circuit. It is used to control the amount of voltage and/or amperage in a circuit. Everything in the circuit causes a resistance (even wire). It is measured in OHMS () 
Resistivity 
the longitudinal electrical resistance of a uniform rod of unit length and unit crosssectional area : the reciprocal of conductivity. Resistance depends on the resistivity of the material. The resistivity is defined as the resistance of a cylinder of the material 1 meter long with a crosssectional area of 1 m^{2}. Resistivity varies with temperature. It is measured in ohms m^{2}/m. (Some texts use ohm m.) 
resultant vector 
Is the sum of two or more vectors. 



scalar quantity 
A quantity that can be described completely with a magnitude. The magnitude is made up of both a number and a unit. Some examples are mass, time, distance, speed, and work. 
Series Circuit 
In this circuit, electrons can flow along one path only. 
slope 
the slope of the line is a ratio of the rise to the run. The change y over the change over x. 
speedaverage(v_{av}) 
Is the total distance traveled divided by the change in time. 
Stroboscope 
An instrument that allows you to see frames of movement and is therefore useful when examining rapid motion. 
Superconductivity 
a complete disappearance of electrical resistance in a substance especially at very low temperatures. 



Tailings 
The waste material from the uranium ore after the uranium has been extracted. This material is slightly radioactive and must be disposed of with care. 
Total Mechnaical Energy 
Is the sum of the kinetic and gravitational potential energy in an object. E_{T} = E_{g} + E_{k} 



Uniform motion 
Is the simplest form of motion. It can be defined as motion in a straight line, in a specific direction at a constant speed. It can also be described as motion with a constant velocity. 





vector 
Is a vector quantity that is represented on a diagram by a line segment with an arrow at one end to indicate direction. Reference coordinates must also be included. The tail of the vector is at its origin and the tip is at the terminal point (the arrow). The length of the vector, drawn to scale, represents its magnitude. 
vector quantity 
A quantity that consists of both magnitude and direction. The magnitude is made up of both a number and a unit. Some examples are position, displacement, velocity, acceleration, force, and weight. 
vector resolution 
Resolving vectors into vector components along the x and yaxes. 
velocity 
Velocity is defined as the displacement of an object divided by the time elapsed. Velocity is usually classified as Average,, Constant, or Instantaneous. The SI units are m/s. 
vibration 
One complete to and fro motion. 
Voltage 
electric potential or potential difference expressed in volts. Also known as electromotive force  it is the force that pushes and pulls electrons through a conductor. 



Weight 
The force of gravity on an object. 
Work (W) 
Is a scalar quantity. It is the product of an applied force and the displacement of an object in the direction of the applied force. The unit for work is a newton.meter (N.m) which equals a Joule (J).





























