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3 years ago

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What is the energy difference between the second excited state and first excited state of an electron in the "box" of size L=1nm

? A) 1.9 eV B) 1.1 eV C) 0.6 eV D) 0.3 eV E) 0.2 eV

1 answer:

jolli1 [7]3 years ago

4 0

I thinks it’s A, tell me if you get it right

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An important diagnostic tool for heart disease is the pressure difference between blood pressure in the heart and in the aorta l

butalik [34]

Answer:

a) f ’’ = f₀ $\frac{1 + \frac{v}{c} }{1- \frac{v}{c} }$ , b) Δf = 2 f₀ $\frac{v}{c}$

Explanation:

a) This is a Doppler effect exercise, which we must solve in two parts in the first the emitter is fixed and in the second when the sound is reflected the emitter is mobile.

Let's look for the frequency (f ’) that the mobile aorta receives, the blood is leaving the aorta or is moving towards the source

f ’= fo $\frac{c+v}{c}$

This sound wave is reflected by the blood that becomes the emitter, mobile and the receiver is fixed.

f ’’ = f’ $\frac{c}{ c-v}$

where c represents the sound velocity in stationary blood

therefore the received frequency is

f ’’ = f₀ $\frac{c}{c-v}$

let's simplify the expression

f ’’ = f₀ \frac{c+v}{c-v}

f ’’ = f₀ $\frac{1 + \frac{v}{c} }{1- \frac{v}{c} }$

b) At the low speed limit v <c, we can expand the quantity

(1 -x)ⁿ = 1 - x + n (n-1) x² + ...

$( 1- \frac{v}{c} ) ^{-1} = 1 + \frac{v}{c}$

f ’’ = fo $( 1+ \frac{v}{c}) ( 1 + \frac{v}{c} )$

f ’’ = fo $( 1 + 2 \frac{v}{c} + \frac{v^2}{ c^2} )$

leave the linear term

f ’’ = f₀ + f₀ 2 $\frac{v}{c}$

the sound difference

f ’’ -f₀ = 2f₀ v/c

Δf = 2 f₀ $\frac{v}{c}$

4 0

3 years ago

A Imagine you derive the following expression by analyzing the physics of a particular system: v2 + 2az. The problem requires so

Nuetrik [128]

Answer:

z = 93.2 m

Explanation:

We can appreciate that this expression is equivalent to the linear motion equation with constant acceleration

v² = v₀² + 2 a d

If we make a term-to-term comparison with the expression obtained, they are equivalent

u² = v² + 2 a z

From here we can clear the position

2 a z = u² –v²

z = (u² –v²) / 2 a

Let's calculate

For the speed to reduce the acceleration must be negative

z = (0 - 21.8²) / 2(- 2.55)

z = 93.2 m

7 0

3 years ago

Which of the following has the lowest density ? A.mineral water b. Water c. Oxygen d. Salt water

tia_tia [17]

Answer:

c

Explanation:

Mineral water, water, and salt water are all liquid solutions, while oxygen is a gas. Gases are less dense than liquids.

7 0

3 years ago

Two 0.40 kg soccer ball collide elastically in a head-on collision. The first ball starts at rest, and the second ball has a spe

yulyashka [42]

Explanation:

Mass of two soccer balls, $m_1=m_2=0.4\ kg$

Initial speed of first ball, $u_1=0$

Initial speed of second ball, $u_2=3.5\ m/s$

After the collision,

Final speed of the second ball, $v_2=0$

(a) The momentum remains conserved. Using the conservation of momentum to find it as :

$m_1u_1+m_2u_2=m_1v_1+m_2v_2$

$v_1$ is the final speed of the first ball

$0.4\times 0+0.4\times 3.5=0.4v_1+0.4\times 0$

$0.4\times 3.5=0.4v_1$

$v_1=3.5\ m/s$

(b) Let $E_1$ is the kinetic energy of the first ball before the collision. It is given by :

$E_1=\dfrac{1}{2}mu_1^2$

$E_1=\dfrac{1}{2}\times 0.4\times 0$

It is at rest, so, the kinetic energy of the first ball before the collision is 0.

(c) After the collision, the second ball comes to rest. So, the kinetic energy of the second ball after the collision is 0.

Hence, this is the required solution.

7 0

3 years ago

Read 2 more answers

Which of the following is most likely to be a secondary source

Anni [7]

Answer:

analyze, assess or interpret an historical event, era, or phenomenon,.

Explanation:

Secondary sources are works that analyze, assess or interpret an historical event, era, or phenomenon, generally utilizing primary sources to do so. Secondary sources often offer a review or a critique. Secondary sources can include books, journal articles, speeches, reviews, research reports, and more.

4 0

2 years ago