Chapter 6 : Earth physics Flashcards
Sound waves. Reflections of sound. Structure of the Earth. Changes in the Earth. Solar and lunar eclipses.
What happens if you pluck the strings of a guitar with more force.
The sound is louder.
What is sound?
Sound is a longitudinal wave caused by vibrations.
What is an echo?
An echo is a reflection of a sound wave.
What is the loudness of a sound measured in?
Decibels
What is a sound wave?
A sound wave is when sound travels from a vibrating object to our ears.
Can sound be heard in space? Explain your answer.
Sound can not be heard because there are no particles in space.
Will sound echo more in an empty room or a room with furniture? Explain your answer.
Sound will echo more in an empty room because there are very few things to absorb the sound as it reflects of surfaces.
In what direction does sound travel?
In all directions.
What kind of surface reflects sound the best?
Large, smooth and flat surfaces.
Name 3 ways in which echo is useful.
- Some animals such as bats use echoes to communicate or find prey.
- Boat use echoes to work out the depth of the water under the boat.
- Echoes can be used to make images from inside the body.
Give one way echoes are useful and explain how it is used.
- Boats use echoes to work out the depth of the water below it.
Sound travels into the water and reflects of the ground. The time taken for the echo to come back can be used to work out the depth.
How can we reduce echoes? Name two ways.
- By adding more furniture such as couches and rugs.
- By adding insulators to the walls.
To hear sound, there must be … and …
- A vibration and a medium containing particles in which sound can travel through.
What are tectonic plates?
Areas of the Earth’s crust that can move.
What are the parts of the Earth’s structure from the surface to the centre.
- Crust
- Mantle
- Outer core
- Inner core
