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3 years ago

What important factor does the ozone layer serve in earth's atmosphere?

1 answer:

3 0

The Ozone layer is responsible for the absorption of harmful radiation from the sun before it hits the surface or exterior structure of our planet. It is known to be a belt of a known occurring gas, known as “ozone” which is sealed around the Earth’s atmosphere. It serves as a shield, which absorbs most of the sun’s ultraviolet radiation.

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Lead atoms occupy a volume of 3 x 10-29 m3. Each atom contributes two free electrons. Calculate the Fermi velocity of lead.

Juliette [100K]

Answer: The Fermi velocity of lead is 64.4 km/s.

Explanation:

To calculate the Fermi velocity, we use the equation:

$V_f=\frac{h}{2\pi m_e}(\frac{3\pi^2N}{V})^{1/3}$

where,

h = Planck's constant = $6.62\times 10^{-34}Js$

$m_e$ = mass of electron = $9.1\times 10^{-31}kg$

N = Number of atoms present in per volume of atom multiplied by number of electrons present in given atom = $\frac{2\times N_A\times V}{M}$

$N_A$ = Avogadro's number = $6.022\times 10^{26}mol^{-1}$ (When the mass is in kilograms)

V = Volume = $3\times 10^{-29}m^3$

M = molecular weight of lead = 207.2 g/mol

Putting values in above equation, we get:

$V_f=\frac{6.62\times 10^{-34}}{2\times 3.14\times (9.1\times 10^{-31})}(\frac{3\times (3.14)^2\times (2\times 6.022\times 10^{23}\times 3\times 10^{-29})}{3\times 10^{-29}\times 207.2})^{1/3}$

$V_f=0.0644\times 10^6m/s=64.4km/s$ (Conversion factor: 1 km = 1000 m)

Hence, the Fermi velocity of lead is 64.4 km/s

4 0

3 years ago

The intensity level of a "Super-Silent" power lawn mower at a distance of 1.0 m is 100 dB. You wake up one morning to find that

Gala2k [10]

Answer:

The intensity level in the room is 63 dB

Explanation:

To calculate the intensity of sound in the room, we use the equation of definition of decibels

β = 10 log (I / Io) (1)

With “I” the sound intensity and “Io” the threshold intensity 1.0 10⁻⁻¹² W/m²

To calculate the intensity we will use the initial data and remember the power of the emitted sound is constant, in addition that the sound propagates in three-dimensional form or on a spherical surface

I = P/A ⇒ P = I A

The area of a sphere is 4 π r², where I can calculate of 1

β/10 = log (I/Io)

I / Io = ${10}^{\beta /10}$

I = Io ${10}^{\beta /10}$

I = 1 10⁻¹² 10⁽¹⁰⁰/¹⁰⁾ = 1 10⁻¹² 10¹⁰

I = 1.0 10⁻² W

With this we can calculate the intensity for a distance of 20 m

I = 1.0 10⁻² / ( 4π 20²)

I = 2.0 10⁻⁶ W/m²

We have already found the intensity at the point of interest, so we can calculate the intensity in decibels at this point with equation 1

β = 10 log(2.0 10⁻⁶ / 1.0 10⁻¹²)

β = 10 log ( 2 10⁶) = 10 6.3

β = 63 dB

The intensity level in the room is 63 dB

5 0

3 years ago

What is the meaning of Choreography for Aerobic Dance?

MakcuM [25]

Aerobic dance has its foundation in dance-inspired movements. It is a cardiovascular workout set to music in a group exercise setting. You do not have to memorize dance moves, as the classes are taught by instructors who verbally tell and visually show the choreography.

4 0

2 years ago

3 physical adaptations of a frog

ICE Princess25 [194]

Water, land. breath using skin and lungs

6 0

3 years ago

The fastest pitched baseball was clocked at 46 m/s. assume that the pitcher exerted his force (assumed to be horizontal and cons

Zielflug [23.3K]

Using the Equation:
v² = vi² + 2 · a · s → Eq.1
where,
v = final velocity
vi = initial velocity
a = acceleration
s = distance

We know that vi = 0 because the ball was at rest initially.

Therefore,

Solving Eq.1 for acceleration,

 v² = vi² + 2 · a · s
v² = 0 + 2 · a · s
v² = 2 · a · s
Rearranging for a,
a = v ²/2·s
Substituting the values,
a = 46²/2×1
a = 1058 m/s²

Now applying Newton's 2nd law of motion,

F = ma
= 0.145×1058

F = 153.4 N

8 0

2 years ago