Sound and space
Loudness and amplitude
Loudness of a sound is a way to describe how quiet
or loud the sound appears.
Loudness depends on two variables;
1) How much the object is vibrating?
2) How far away the vibrating object is?
The greater the distance of each vibration in the
object, the greater the distance that particles in air
will be pushed.
The maximum distance that particles move, either
forward or backward in a sound wave, is called as
amplitude.
As the amplitude of a sound wave increases, the
loudness of the sound increases.
 Quieter sound has a smaller amplitude.
 Louder sound has a larger amplitude.
Pitch and Frequency.
Pitch of a sound of a sound is how high or low the
sound appears on a musical note.
The number of vibrations in each second is called
frequency.
The frequency of a sound determines its pitch.
Faster the vibration, higher the pitch of the sound.
A wave with a higher frequency will have more
waves in the same time.
 Higher frequency has higher pitch.
 Lower frequency has lower pitch.
If the amplitude of higher and lower pitch are the
same, that means the loudness of both sounds are
the same.
Interference of sound
Interference is what happens when two or more
waves meet each other. The effect that is produced
when the waves meet each other is called
interference.
Interference is easiest to detect when the waves have
the same frequency and the same amplitude.
Waves will reinforce when they meet with peaks
together and with the troughs together.
1. Reinforcement / Constructive Interference
2. Cancelation/ Destructive Interference
Constructive wave interference
The wave interference is said to be a constructive
wave interference if the crest of a wave meets the
crest of another wave of the same frequency at the
same point.
or
Constructive wave interference is a wave interference
which occurs when in phase waves meets with each
other and forms a new wave with greater amplitude.
Destructive wave interference
The wave interference is said to be a destructive
wave interference if the crest of a wave meets the
trough of another wave of the same frequency.
or
Destructive wave interference is a wave interference
which occurs when out of phase waves meets with
each other and forms a new wave with lower
amplitude or zero amplitude.
Formation of moon
Q. How does moon form?
The most accepted theory for the formation of the
moon today is the giant-impact theory.
It proposes that the Moon formed during a collision
between the Earth and another small planet, about
the size of Mars. The debris from this impact
collected in an orbit around Earth to form the Moon.
The colliding body is called Theia.
Collision theory;
One of the theories for the formation of the Moon
A newly formed planet, about the same size as Mars,
collided with the newly formed Earth. The collision
would have caused rocks and dust to break away
from the both the planets. The Moon formed when
the rocks and the dust was pulled together by
gravity.
Evidence that supports the collision theory
- The Moon is less dense than Earth.
- The Moon has small iron core, similar to the
Earth.
- The composition of rocks on the Earth and the
Moon are the same.
Evidence that contradicts the collision theory
- The surface of Earth does not appear to ever
have been molten. A collision that formed Moon
would have caused the surface of the Earth to
melt. The surface would have later solidified.
Nebulae
Nebulae are could of dust and gas in space.
The gases found in nebulae are mostly hydrogen
and a smaller quantity of helium.
Stellar nurseries.
A stellar nursey is an area in space where starts are
formed.
When the mass of the dust and the gas collects
together and becomes larger, the force f gravity
pulling inward increases. The pressure inside the new
star also gets large. The pressure can cause atoms to
react with each other, causing the new star to give
out heat and light.
Tectonics
Q. what are Tectonic plates?
Ans- Tectonic plates are the gigantic pieces of the
Earth crust and upper most mantle. The outermost
layer of the Earth is called the crust and it is broken
into large pieces called tectonic plates.
They are made up of oceanic crust and continental
crust. Earthquakes occur around mid-ocean ridges
and the large faults which mark the edges of the
plates.
Evidences of Tectonic Plates:
1. Jigsaw appearance of continental coasts
2. Fossil record
3. Alignment of magnetic materials in the Earth’s
crust
4. Position of volcanoes