Science_Illustrated_Australia_-_Issue70_2019

22 | SCIENCE ILLUSTRATED

When the pressure in the eustachian tube is equalised with the pressure

in the outer ear, the eardrum falls back into place with a ‘pop’.

Why do my ears ‘pop’?

PHYSICS IN PRACTICE · Do stones fall more slowly on a high mountain or in a low valley?

A stone falls faster when dropped at the top of a mountain than

when dropped in a low valley, because the air is thinner on the

mountain, and the friction from air drag is therefore lower.

If the differing air drags were not a factor, the stone would actually

fall more slowly on the mountain, because it is further away from

the Earth’s centre, so the gravitational acceleration is lower.

HUMANS The ‘pop’ of the ears
experienced in a plane during
ascent and descent comes as the
eardrum falls back into place.
The middle ear and the pharynx
are connected via the eustachian
tube, which is shut most of the
time. But when you swallow or
yawn, the tube opens to equalise
the pressure on either side of the
eardrum. During a flight, the

pressure changes in the cabin of the

aircraft – and so affects the external

sections of the ear. By yawning or

swallowing, you can bring the areas

behind the eardrum to the same

pressure, making the drum fall back

into place. But the pop of a yawn

doesn’t always come from the

auditory canal; a small buffer disc

of cartilage in the jaw joint can also

‘pop’ when the mouth opens.

SU

IZA

PER

UAN

A

SH

UTT

ERS

TOC

K

MOUNT

HUASCARÁN

GRAVITATIONAL

ACCELERATION:

On Mount Huascarán in

Peru, it is 9.76392 m/s^2 ,

slightly weaker than at the

Earth's surface.

AIR DRAG:

The air is thinner, so the

stone falls faster.

EARTH’S SURFACE

GRAVITATIONAL

ACCELERATION:

At the Earth's surface,

it is approximately

9.81 m/s^2.

AIR DRAG:

At the Earth’s surface the

air offers higher resistance,

so the stone falls more

slowly than on a mountain.

EUSTACHIAN

TUBE

EARDRUM

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