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4 years ago

What is accommodation in the eye? how are the muscles involved in this process?

1 answer:

3 0

"Accomodation" is the name we give to our eyes' ability to change their
focus for different distances.

Our eye does this by changing the thickness of its lens, making the lens
thicker to see nearer things, and thinner to see distant things.

The lens in the eye is suspended by a circular muscle all around it.
The muscle can pull on the circumference of the lens to make it wider
and thinner, or relax to make it narrower and thicker.

In the modern age of medical miracles that we live in, if the lens of
a person's eye is injured or becomes cloudy, an ophthalmologist can
replace it with an artificial one, and the person can see again ! But then,
the process of accommodation doesn't work any more. That artificial lens
stays focused at the same distance all the time, and the person needs
glasses for other distances.

I can tell you that it's not really a big deal. The lenses in BOTH of my eyes
developed "cataracts", and were replaced with artificial lenses.
I had a choice ! I could have lenses that are good for distance, and wear
glasses for reading. OR I could choose lenses that are good for reading
and put on glasses to see things in the distance. I chose lenses for distance.
I can SEE again, and I put on reading glasses when I'm reading.

It's really a miracle when you think about it.

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A woman is standing in the ocean, and she notices that after a wave crest passes by, five more crests pass in a time of 50.2 s.

lorasvet [3.4K]

Explanation:

(a) The period of a wave is the time required for one complete cycle. In this case, we have the time of five cycles. So:

$T=\frac{t}{n}\\\\T=\frac{50.2s}{5}\\T=10.04s$

(b) The frequency of a wave is inversely proportional to its period:

$f=\frac{1}{T}\\f=\frac{1}{10.04s}\\f=0.01Hz$

(c) The wavelength is the distance between two successive crests, so:

$\lambda=30.2m$

(d) The speed of a wave is defined as:

$v=f\lambda\\v=(0.1Hz)(30.2m)\\v=3.02\frac{m}{s}$

8 0

3 years ago

A plasma wave moving through a plasma has a frequency of 109 Hz and a speed of 3.0 × 107 m/s. What is the wavelength of this wav

tigry1 [53]

Answer:0.27*10^{6} (m)

Explanation:

with a wave we know that speed= wavelenght* frecuency so

wavelenght= 3*10^{7} / 109 = 0.27*10^{6} (m)

8 0

3 years ago

an athlete in a hammer-throw event swings a 7.0-kilogram hammer in a horizontal circle at a constant speed of 12 meters per seco

Semenov [28]

Answer:

ac = 72 m/s²

Fc = 504 N

Explanation:

We can find the centripetal acceleration of the hammer by using the following formula:

$a_c = \frac{v^2}{r}$

where,

ac = centripetal acceleration = ?

v = constant speed = 12 m/s

r = radius = 2 m

Therefore,

$a_c = \frac{(12\ m/s)^2}{2\ m}$

ac = 72 m/s²

Now, the centripetal force applied by the athlete on the hammer will be:

$F_c = ma_c\\F_c = (7\ kg)(72\ m/s^2)$

Fc = 504 N

6 0

3 years ago

A vertical spring with k=490N/m is standing on the ground. You are holding a 5.0kg block just above the spring, not quite touchi

WARRIOR [948]

Answer:

Compression in the spring, x = 0.20 m

Explanation:

Given that,

Spring constant of the spring, k = 490 N/m

Mass of the block, m = 5 kg

To find,

Compression in the spring.

Solution,

Since the block is suddenly dropped on the spring gravitational potential energy of block converts into elastic potential energy of spring. Its expression is given by :

$mgx=\dfrac{1}{2}kx^2$