The document describes a physics problem where an object emits a sound at the surface of the sea. The sound wave has a wavelength of 1m in air and 4.5m in sea water, and the speed of sound in air is 340m/s. The echo is received 0.5 seconds later. Using the equations relating wavelength, frequency and speed, and that frequency does not change between mediums, the document calculates that the depth of the sea is 382.5m.
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Lo 7(2)
1. Yiying
Lin
15621148
LO
7/8
Short
answer
question:
The
sound
produced
by
an
object
has
a
wavelength
1m
in
the
air;
the
wave
speed
is
340
meters
per
second.
It
has
a
wavelength
4.5m
in
the
sea.
This
object
emits
a
sound
at
the
surface
of
the
sea,
and
the
echo
can
be
received
after
0.5
second.
Therefore,
how
deep
is
the
sea
is?
Answer:
use
both
v=了f
and
wave
propagation
to
solve
this
question.
In
different
mediums,
same
sound
waves
will
have
same
frequency.
Frequency=
vair/了air
In
the
sea:
vsea=vair(了sea/了air)=1530m/s
h
=
vsea(t/2)=1530x0.5x0.2
=
382.5m