Radioactive Decay Cindy So

Curvebank Project Website with many mathematical curves Information on curves Animation of curve me.htm me.htm

What is Radioactive decay? Decay is occurs in the parent isotope creates a daughter isotope Decay to form a more stable atom Readjustment of neutrons and protons Random process Impossible to predict the decay of individual atoms

Why is it important? Used to determine dates of objects Uranium-lead dating Highly respected Error of dates of three billion years old is no more than two million years Potassium-argon dating Carbon-14 date more recent objects

Carbon-14 dating chart

Earth’s Age 4.55 billion years Compromise of two ages Zircon - oldest known minerals is about billion years Ca-Al-rich inclusions – oldest known solid constituents within meteorites – are billion years old

General Equation Exponential decay: A = A o e kt Calculations with potassium-argon dating A = A o e kt = 1 e(-5.29x )t ln(0.945) = (-5.29x )t t = 107 million years

Half-life Referred using half-lifes Time for radioactive substance to decay by half Calculation using carbon-14 A = A o e kt 0.5 = 1 e ( )t ln(0.5) = ( ) = t T = 5728 years

Types of decay Each radioactive isotope decay differently Carbon-14 has half-life of 5730 years Cobalt-60 has half-life of years Sodium-24 has half-life of 18 hours Krypton-81 has half-life of 13 seconds

Goal of project Main goal: graph the radioactive decay curve Information needed: Range of time (x-axis) Decay rate and its type Not needed Amount (y-axis)

Calculations Split time into 500 sections Used equation to calculate amount remaining Needed to adjust the graph points into the window screen

Calculations new.x = Ax + C new.y = By + D C = window.left – A * graph.left D = window.bottom – B * graph.bottom

Mapping points

A = (400-40) / (2-0) = 180 B = (300-60) / (1-0) = 240 C = 40 – (180 * 0) = 40 D = 60 – (240 * 0) = 60 new.x = 180x + 40 new.y = 240y + 60

Check figures new.x = 180x + 40 new.y = 240y + 60 (2,1)  (400,300) (0,0)  (40,60)

JAR files Java TM Archive (JAR) bundle multiple files into a single archive file. contains the class files and auxiliary resources associated with applets and applications.

Benefits of JAR Security Decreased download time Compression Packaging for extensions Package Sealing Package Versioning Portability

Creating JAR files jar cf jar-file input-file(s) jar tf jar-file

Demo y/radiodecay.htm

The End