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2 years ago

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1 answer:

7 0

A group of students toured a limestone cave in northwest Georgia.
Which of these best explains how the limestone caves in Georgia were formed?
A. Plant roots split the rock.

B. Acidic water dissolved the rock.

C. Animals burrowed into the rock.

D. Ice formed and broke up the rock.

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The velocity of sound on a particular day outside is 331 meters/second. What is the frequency of a tone if it has a wavelength o

Levart [38]

I think c hope it help

3 0

3 years ago

Read 2 more answers

A ball is dropped from rest at point O. After falling for some time, it passes by a window of height 3.3 m and it does so in 0.2

stiv31 [10]

Answer:

Speed at which the ball passes the window’s top = 10.89 m/s

Explanation:

Height of window = 3.3 m

Time took to cover window = 0.27 s

Initial velocity, u = 0m/s

We have equation of motion s = ut + 0.5at²

For the top of window (position A)

$s_A=0\times t_A+0.5\times 9.81t_A^2\\\\s_A=4.905t_A^2$

For the bottom of window (position B)

$s_B=0\times t_B+0.5\times 9.81t_B^2\\\\s_A=4.905t_B^2$

$\texttt{Height of window=}s_B-s_A=3.3\\\\4.905t_B^2-4.905t_A^2=3.3\\\\t_B^2-t_A^2=0.673$

We also have

$t_B-t_A=0.27$

Solving

$t_B=0.27+t_A\\\\(0.27+t_A)^2-t_A^2=0.673\\\\t_A^2+0.54t_A+0.0729-t_A^2=0.673\\\\t_A=1.11s\\\\t_B=0.27+1.11=1.38s$

So after 1.11 seconds ball reaches at top of window,

We have equation of motion v = u + at

$v_A=0+9.81\times 1.11=10.89m/s$

Speed at which the ball passes the window’s top = 10.89 m/s

7 0

3 years ago

Why is everything spinning? Moons, planets and stars all rotate on their axes, moons orbit planets, planets orbit stars, spiral

kow [346]

Answer:

Conservation of angular momentum

Explanation:

When the objects spread in universe after big bang, because of the tremendous force , they gained angular momentum and started to rotate. Since, then the object continue to rotate on their axis because of conservation of angular momentum. In vacuum of space there no other forces that can stop these rotation, therefore, they continue to rotate.

4 0

3 years ago

When a nerve cell depolarizes, charge is transferred across the cell membrane, changing the potential difference. For a typical

laila [671]

Answer:

I = 18 x 10⁻⁹ A = 18 nA

Explanation:

The current is defined as the flow of charge per unit time. Therefore,

I = q/t

where,

I = Average Current passing through nerve cell

q = Total flow of charges through nerve cell

t = time period of flow of charges

Here, in our case:

I = ?

q = (9 pC)(1 x 10⁻¹² C/1 pC) = 9 x 10⁻¹² C

t = (0.5 ms)(1 x 10⁻³ s/1 ms) = 5 x 10⁻⁴ s

Therefore,

I = (9 x 10⁻¹² C)/(5 x 10⁻⁴ s)

6 0

2 years ago

A film of soapy water on top of a plastic cutting board has a thickness of 255 nm. What wavelength and color is most strongly re

Alona [7]

Answer:

the reflected wavelength is lano = 4.55 10⁻⁷ m which corresponds to the blue color

Explanation:

This is a case of reflection interference, we must be careful

* There is a 180º phase change when light passes from the air to the soap film (n = 1,339), but there is no phase change when passing from the pomp to the plastic (n = 1.3)

* the wavelength within the film is modulated by the refractive index

λₙ = λ₀ / n

if we consider these relationships the condition for constructive interference is

2 t = (m + ½) λₙ

2t = (m + ½) λ₀ / n

λ₀ = 2t n / (m + ½)

we substitute the values

λ₀= 2 255 10⁻⁹ 1,339 / (m + ½)

λ₀ = 6.829 10⁻⁷ (m + ½)

let's calculate the wavelength for various interference orders

m = 0

λ₀ = 6.829 10⁻⁷/ ( 0 + ½ )

λ₀ = 13.6 10⁻⁷

it is not visible

m = 1

λ₀ = 6,829 10⁻⁷/ (1 + ½)

λ₀ = 4.55 10⁻⁷

color blue

m = 2

λ₀ = 6.829 10⁻⁷ / (2 + ½)

λ₀ = 2,7 10⁻⁷

it is not visible

therefore the reflected wavelength is lano = 4.55 10⁻⁷ m which corresponds to the blue color

5 0

3 years ago