Why Study Physics? Any ideas?

An understanding of the world around you

Innovation and invention to make your life easier

Develop your analytical skills

You will always win that argument

It opens many opportunities in and out of the sciences

Where can I go with Physics?

Lets talk money

What’s in the course? AS91168 4 Internal AS91189 3 AS91170 External Topic Credits How Assessed AS91168 2.1 Carry out a practical physics investigation that leads to a non- linear mathematical relationship 4 Internal AS91189 2.2 Demonstrate understanding of physics relevant to a selected context 3 AS91170 2.3. Demonstrate understanding of waves External AS91171 2.4 Demonstrate understanding of mechanics 6 AS91172 2.5 Demonstrate understanding of atoms and radioactivity AS91173 2.6 Demonstrate understanding of electricity and electromagnetism Total Possible Credits 26

What’s the plan? Term 1 Term 2 Term 3 Term 4 Content Important Dates Review Mathematical and Practical Skills 2.4 Mechanics Practise 2.1 Week 8 Practise 2.4 Week 10 Term 2 2.3 Waves 2.5 Atomic Physics 2.2 Physics in Context Week 5 2.2 / 2.5 Internals (3+3 credits) Due week 10 MID YEAR EXAM: MECHANICS, WAVES, ATOMIC – week 8 Term 3 2.6 Electricity 2.1 Investigative Physics 2.1 Internal (4 credits) Week 3 ALL RESITS Week 11 END OF YEAR EXAM: MECHANICS, WAVES, ELECTRICITY – week 10 Term 4 Revision for external exams Study leave NCEA Physics Exam

Maths Skills You need good algebra to rearrange equations You need trigonometry to deal with angles You need good graph skills to show relationships You need knowledge of standard form to deal with very big and very small numbers

Algebra Most equations can be put into a triangle: P = IV  Others need the algebra rules to rearrange: a2 = b2 + c2 P V I

Practise Rearranging Equations

Trigonometry Life doesn’t always occur horizontally... SOH CAH TOA will guide you

Practise Trigonometry

Graphs – what is the point? Graphs prove a relationship between two variables: What are the dependent and independent variables? Describe the relationship.

Plot these graph and describe the relationship Mass (g) Volume (cm3) 8.4 1.0 17.1 2.0 25.5 3.0 34.2 4.0 42.3 5.0 51.0 6.0 Distance (m) Time (s) 2 1 8 18 3 32 4 50 5 What I should see: Correctly scaled axes (that fill the page) Axes labelled with symbol/quantity AND unit Points all plotted correctly with ‘x’ or ‘o’ Line or curve of best fit

Common Relationships in Physics Linear : Square: Inverse: Inverse squared:

Proportional:∝ Linear Relationships: distance ∝ velocity voltage ∝ current Square relationships: Energy ∝ velocity2 Inverse relationships: Frequency ∝1/period of oscillation Acceleration ∝ 1 / mass Inverse squared relationships: Gravitational Force ∝ 1 / radius2

Graph Skills Describe the relationship between Frequency and Voltage Form an equation for this line by calculating the gradient and y-intercept.

Standard or Scientific Notation Do you know this number, 300,000,000 m/s? It's the Speed of light ! How about this one, 0.000 000 000 753 kg. ? This is the mass of a dust particle! Scientists have developed a shorter method to express very large numbers. This method is based on powers of the base number 10. The number 123,000,000,000 in scientific notation is written as: Coefficient Exponent

How do you do it? Drop the point after the first non zero number Count the number of places from the point till the end of the number to get the exponent. Numbers less smaller than 1 will have a negative exponent. A millionth of a second is: 0.000001 sec. Write this in standard notation.

Practise these 3400000 0.0000098 4050 0.000105

Powers of 10 Prefix Number Power Giga, G 1 000 000 000 109 Mega, M 106 Kilo, k 1 000 103 Milli, m 0.001 10-3 Micro, μ 0.000001 10-6 Nano, n 0.000000001 10-9 Pico, p 0.000000000001 10-12

Interchangeable Numbers Decimal Standard Form Prefix form 0.0005 kg 2.4x109 N 50 000 000 W 450 kHz 2.99x108 m s-1 700 nm

Significant Figures The first non-zero number is the first significant figure So: 0.000105 has 3 significant figures 50 000 000 has 1 significant figure The number of significant figures in a calculation is dependent on the least accurate measurement: 3.0456 V x 20 s = 61 V s (1.s.f)

How many sf? 2000 3.045 55 10004000 0.00056 0.10005 66.6

Sig Figs a) (6.01x10-6 m) x (1x1013 s-1) = b) 2.002 x 0.0001 = c) 50600 x 4.565 =

Review Algebra Trigonometry Graphs Scientific Notation Significant figures