photo credit Nasa / Goddard Space Flight Center / Reto Stöckli Key Facts

P1.2 What do we know about the Earth and how it is changing? P1: The Earth in the Universe Structure of the Earth Crust

Mantle

Outer core

Inner core The wave equation wave speed = frequency x wavelength Tectonic plates What drives them?

Heat from the core moves through the mantle as convection currents

Remember hot liquids and gases are less dense and rise

This transfers heat from somewhere hot to somewhere cooler P and S waves P waves

Faster

Pass through solid and liqiud

Less destructive

S waves

Slower

Pass through solids can't pass through liquid core

More destructive. Alfred Wegener Wegeners Clues

Jigsaw "Geometric" fit of continents

Matching rocks

Matching fossils Vindication Scientists eventually accepted Wegener's ideas because of new evidence;

Sea floor spreading

Magnetic reversal patterns Why did others reject his theory?

Not a geologist

Was unable to measure drift

had no plausible explanation of drift Example:

Frequency = 165Hz

Wavelength = 2m

What is the wave speed?

Wave speed = frequency x wavelength

Wave speed = 165Hz x 2m

Wave speed = 330m/s The wave equation You can work out the speed of a wave if you know…..

1. How many waves pass each second.

(the frequency).

2. How long each wave is.

(the wavelength) How fast do waves travel? LONGTUDINAL WAVES

P wave

The wave moves along in the same direction as the disturbance or vibration. TRANSVERSE WAVES

S wave

The wave moves at right angles to the disturbance or vibration. TRANSVERSE AND LONGITUDINAL We cannot see light or sound waves so looking at waves moving along a spring can help us learn more about them.

There are 2 main types of waves, they carry a lot of energy from one place to another.

The 2 types are called TRANSVERSE AND LONGITUDINAL waves. REMEMBER LAST LESSON…. 6. What is the speed of sound in water if a 5kHz* sound has a wavelength of 0.3m?

7. is the speed of a radio wave of wavelength 1500m and frequency 200kHz*?

8. What is the frequency of a radio wave of wavelength 100m and speed 300,000,000m/s?

9. What is the frequency of a microwave of wavelength 60cm* if its speed is 300,000,000m/s?

10. What is the wavelength of Rock FM if its frequency is 97.4MHz* and its speed is 300,000,000m/s?

kHz = 1000Hz MHz = 1000000Hz 1 What is the speed of a water wave if it has a frequency of 4Hz and a wavelength of 1.5m?

2 What is the frequency of a sound wave if its wavelength is 3m and the speed of sound in air is 330m/s?

3 What is the wavelength of a sound wave if its frequency is 200Hz and the speed of sound in air is 340m/s?

4 What is the wavelength of a wave in a slinky spring if its frequency is 8Hz and its speed is 6m/s?

5 What is the speed of a wave in a slinky spring if its frequency is 23Hz and its wavelength is 15cm*? Ten questions you did in class, try them again! Using your formula triangle means you can work out what equation to use if you need to find wavelength and frequency. Hz m (or km) m/s (watch this they may use km/s) wavelength frequency x Wave speed Wave speed

WAVE SPEED = FREQUENCY X WAVELENGTH

(m/s) (Hz) (m)

Hz is short for HERTZ which is the unit of measurement for frequency. The wave equation Direction of travel Vibration Wavelength –

Trough to Trough Wavelength – Peak to Peak Lesson Objectives:

To be able to identify amplitude, wavelength and frequency on a diagram of a transverse wave.

To be able to use the equation for wave speed Describing transverse waves and

the wave equation Frequency – The number of waves per second. If one wave passes in one second it has a frequency of one Hertz or Hz. This is the unit of frequency. Time (s) Height (m) 2 1 1 2 0 2 1 Direction of travel Vibration Amplitude Amplitude Wavelength Wavelength Do the calculation.

Write the answer clearly and

Don’t forget the UNITS. Put in the numbers you have been given

In the question.

Check they are in the correct positions. Write out the equation in full

Rearrange it if you need to using your

Formula triangle THREE STEPS TO EXAM MARKS Find the wave speeds….

1) Wavelength = 3m, Frequency = 100Hz

2) Wavelength = 2m, Frequency = 135Hz

3) Wavelength = 0.5m, Frequency = 200Hz

Remember the 3 step method for equations – YOU MUST DO THIS TO GET FULL EXAM MARKS!! THREE STEPS TO EXAM MARKS

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# OCR Twenty first century Science GCSE P1

P1 revision