a) Longitudinal waves above 20,000 Hz Ultrasound is …….. Longitudinal waves below 20 Hz Longitudinal waves above 20,000 Hz Transverse waves above 20,000 Hz Answer. a) Longitudinal waves above 20,000 Hz

Answer c) Between 20-20,000 Hz 2) Human hearing range is; Above 20,000 Hz Below 20 Hz Between 20-20,000 Hz Answer c) Between 20-20,000 Hz

3) How is ultrasound used for in foetal scanning? Answer Ultrasound waves pass through the body; at boundaries between two different media; some waves are reflected back and detected to produce a computer image

4)How is Sonar used in boats and submarines to detect stuff in water? Answer Boats and submarines emit ultrasound, which is reflected off the object (ie boats, sea bed, marine animals) The time-delay between emitting and detecting the waves is used to calculate how far the other object is using S=d/t

rearrange, distance = speed x time 5) Calculation: A pulse of ultrasound takes 5 seconds to travel from a boat to a ship wreck under the sea and back again. How far away is the shipwreck? (speed of sound in water = 1520 m/s) Answer Speed = distance/time rearrange, distance = speed x time = 1520 x 5 = 7200 m Its 5s there and back so the ship wreck is only half the distance away so divide by 2. = 7200/2 = 3600 m

Longitudinal waves below 20 Hz 6) Infrasound is …….. Longitudinal waves below 20 Hz Longitudinal waves above 20 Hz Transverse waves above 20,000 Hz Answer Longitudinal waves below 20 Hz

7) Explain how animals use infrasound? Answer. Elephants use infrasound to communicate with other members of their heard over long distances. Tigers use infrasound in the growls and roars which can be heard by rivals or mates

Infrasound is long wavelength, 8) Why can some volcanic eruptions be detected at a distance? Answer Infrasound is long wavelength, that means they can travel long distances and diffract around objects.

Answer False statements are: 9) Which of these statements are false? Low frequency, long wavelength sounds travel further. Larger animals (elephant) make higher frequency sounds compared to little ones (mice). Volcanic eruptions make high frequency sounds that can be heard from a long distance. Answer False statements are: 2. Larger animals (elephant) make higher frequency sounds compared to little ones (mice). 3. Volcanic eruptions make high frequency sounds that can be heard from a long distance

Answer. False statements are: 10) Which of the following statements are false? 1. Sounds travel further in air then in water. 2. Whales can communicate over larger distances than elephants can. 3. Animals that can use infrasound can communicate further distances than animals that use higher frequencies. Answer. False statements are: 1. Sounds travel further in air then in water.

c) Inner core; outer core; mantle; crust 11) The structure of the earth from inside out are: Crust, mantle, outer core; inner core outer core; mantle; inner core; crust Inner core; outer core; mantle; crust Answer. c) Inner core; outer core; mantle; crust

Answer. Inner core –solid Outer core -liquid 12) What is the inner core and outer made from? Answer. Inner core –solid Outer core -liquid

Heat is produced, causing convection currents. 13) What is the mantle made from? Answer Molten rock Heat is produced, causing convection currents.

14) Explain how heat from the mantle causes earth quakes? (3) Answer Heat from the mantle produce convection currents; causing the plates to move At plate boundaries, plates may rub against each other, causing pressure to build up. Sudden release of pressure as a result of the plates sliding past each other causes an earth quake.

15) Why is it difficult to predict an earth quake? (3) Answer Earthquakes are totally random – although there are areas where they are more likely to happen than others (near fault lines). The fault line has a build up of stresses and any part of that fault line could snap out of line at any moment.

Answer. Earthquakes Explosions 16). Give two ways seismic waves are created Answer. Earthquakes Explosions

17). What instrument is used to detect seismic waves created from an earth quake? Answer Seismometer.

18) What are the two types of seismic waves? Answer. P waves S waves

19) What are the properties of P-waves? (4) Answer. These are Push-Pull waves They are longitudinal They can travel through liquid and solid so they can travel through the earth’s core. They travel fast. They are bent by the changing density of the rock. They are bent sharply when the material changes suddenly.

They are Side to Side waves. They are transverse 20) What are the properties of S-waves ?(4) Answer. They are Side to Side waves. They are transverse They can only travel through solids. They are slower than P-waves. They are bent by the changing density of the rock. They are bent sharply when the material changes suddenly

Answer. They are reflected and refracted 21) What happens when seismic waves reach a boundary between different layers of the earth? Answer. They are reflected and refracted

22) What is the phenomenon called which causes the waves to change speed and direction? Reflection Refraction Diffraction Answer. b) Refraction

23) Why does the speed and direction (refraction) of the seismic wave change? Answer When there is a change in density-between different layers of material.ie between mantle and the outer core?

The wave speed changes abruptly and and the path has a kink 24) When there is a gradual change in speed a curved path is made by the wave, what happens when there is a sudden change in properties/densities between layers? Answer The wave speed changes abruptly and and the path has a kink

A) P-waves-they travel the fastest. 25) Which waves are detected first by a seismometer travelling from the epicentre of an earth quake. P-waves S-waves Answer A) P-waves-they travel the fastest.

26) What does arrival time mean? Answer The time taken for a wave (P-wave or S-wave) to travel from the epicentre of the earth quake to the seismometer?

Describe how scientists use P waves and S waves to locate the position of an underground earthquake (6). Seismic waves are detected by seisometers You need at least 3 seisometers The arrival time of s waves will be slower then p waves. The further the seisometer is away from earth quake the greater the difference between the arrival times. Distance can be worked out because the arrival time is known A circle is drawn to indicate the distance The point at which three circles meet is called the epicentre