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myrzilka [38]
4 years ago
7

An electron is confined to a one dimensional region, bounded by an infinite potential. If the energy of the electron in its firs

t excited state is 40 meV, what is its energy in its ground state? A. 40 me V B. 80 meV C. 20 meV D. O meV E. 10 meV
Physics
1 answer:
OLga [1]4 years ago
4 0

Answer:

The energy in its ground state is 10 meV.

Explanation:

It is given that,

The energy of the electron in its first excited state is 40 meV.

Energy of the electron in any state is given by :

E=\dfrac{n^2\pi^2h^2}{8mL^2}

For ground state, n = 1

E_1=\dfrac{\pi^2h^2}{8mL^2}.............(1)

For first excited state, n = 2

40=\dfrac{2^2\pi^2h^2}{8mL^2}.............(2)

Dividing equation (1) and (2), we get :

\dfrac{E_1}{40}=\dfrac{1}{4}

E_1=10\ meV

So, the energy in its ground state is 10 meV. Hence, this is the required solution.

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Answer:

A Ray I believe since it sounds like it.

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4 years ago
Physics student is dropped. If they reach the floor at a speed of 3.2 m/s, from what height did they fall?
Mekhanik [1.2K]

Answer:

0.52 m

Explanation:

The motion of the studnet is an accelerated motion, with constant acceleration g=9.8 m/s^2 (acceleration of gravity) toward the ground. We can find the distance covered by the student (which is equal to the height from which he falls) by using the SUVAT equation:

v^2 -u^2 = 2ad

where

v = 3.2 m/s is the final speed

u = 0 is the initial speed

a = 9.8 m/s^2 is the acceleration

d is the distance covered

By re-arranging the equation, we find:

d=\frac{v^2-u^2}{2a}=\frac{(3.2 m/s)^2-0}{2(9.8 m/s^2)}=0.52 m

5 0
4 years ago
If the volume of the balloon is 500 m3m3 and the surrounding air is at 15.0 ∘C∘C, what must the temperature of the air in the ba
Tresset [83]

Answer:

Temperature of the air in the balloon = 272°C

Explanation:

Given:

Volume of balloon = 500 m³

Air temperature = 15° C = 273 + 15 = 288 K

Total weight = 290 kg

Density of air = 1.23 kg/m³

Find:

Temperature of the air in the balloon

Computation:

Density of hot air = Density of air - [Total weight / Volume of balloon]

Density of hot air = 1.23 - [290 - 500]

Density of hot air = 0.65 kg/m³

[Density of hot air][Temperature of the air in the balloon] = [Density of air][Air temperature ]

Temperature of the air in the balloon = [(1.23)(288)]/(0.65)

Temperature of the air in the balloon = 544.98

Temperature of the air in the balloon = 545 K

Temperature of the air in the balloon = 545 - 273 = 272°C

8 0
3 years ago
A rock with mass m = 4.00 kg falls from rest in a viscous medium. The rock is acted on by a net constant downward force of F = 1
pogonyaev

Answer:

a) 4.35 m/s²

b) 2.73 m/s²

c) 7.25 m/s

d) 8.06 m/s

e) At t = 2 s

x = 16.5 m

v = 7.88 m/s

a = 0.099 m/s²

f) t = 0.743 s

Explanation:

Force balance on the rock

ma = 17.4 - F

4a = 17.4 - kv

4a = 17.4 - 2.16v

a) At the initial instant, F = kv = 0

4a = 17.4

a = 4.35 m/s²

b) When v = 3 m/s

4a = 17.4 - (2.16)(3) = 10.92

a = 2.73 m/s²

c) a₀ = 4.35 m/s²

0.1 a₀ = 0.435 m/s²

4a = 17.4 - 2.16v

4(0.435) = 17.4 - 2.16v

1.74 = 17.4 - 2.16v

2.16v = 15.66

v = 7.25 m/s

d) Terminal speed is when the body stops accelerating in the fluid

When a = 0

0 = 17.4 - 2.16v

2.16 v = 17.4

v = 8.06 m/s

e) 4a = 17.4 - 2.16v

a = 4.35 - 0.54 v

But a = dv/dt

(dv/dt) = 4.35 - 0.54v

∫ dv/(4.35 - 0.54v) = ∫ dt

Integrating the left hand side from 0 to v and the right hand side from 0 to t

- 1.852 In (4.35 - 0.54v) = t

In (4.35 - 0.54v) = - 0.54 t

4.35 - 0.54v = e⁻⁰•⁵⁴ᵗ

0.54v = 4.35 - e⁻⁰•⁵⁴ᵗ

v = 8.06 - 0.54 e⁻⁰•⁵⁴ᵗ

Then, v = dx/dt

(dx/dt) = 8.06 - 0.54 e⁻⁰•⁵⁴ᵗ

dx = (8.06 - 0.54 e⁻⁰•⁵⁴ᵗ) dt

∫ dx = ∫ (8.06 - 0.54 e⁻⁰•⁵⁴ᵗ) dt

Integrating the left hand side from 0 to x and the right hand side from 0 to t

x = 8.06t + e⁻⁰•⁵⁴ᵗ

Acceleration too can be obtained as a function of time

since v = 8.06 - 0.54 e⁻⁰•⁵⁴ᵗ and a = dv/dt

a = 0.54² e⁻⁰•⁵⁴ᵗ = 0.2916 e⁻⁰•⁵⁴ᵗ

At t = 2 s

Coordinate

x = 8.06t + e⁻⁰•⁵⁴ᵗ

x = (8.06)(2) + e^(-1.08) = 16.5 m down into the fluid.

Velocity

v = 8.06 - 0.54 e⁻⁰•⁵⁴ᵗ

v = 8.06 - 0.54 e^(-1.08) = 7.88 m/s

Acceleration

a = 0.2916 e⁻⁰•⁵⁴ᵗ

a = 0.2916 e^(-1.08) = 0.099 m/s²

f) t = ? When v = 0.9 × 8.06 = 7.254 m/s

v = 8.06 - 0.54 e⁻⁰•⁵⁴ᵗ

7.254 = 8.06 - 0.54e⁻⁰•⁵⁴ᵗ

- 0.806 = - 0.54 e⁻⁰•⁵⁴ᵗ

e⁻⁰•⁵⁴ᵗ = 1.493

0.54t = In 1.493 = 0.401

t = 0.743 s.

6 0
3 years ago
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e-lub [12.9K]

Answer:

750,000

Explanation:

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Hope this helps :p

7 0
3 years ago
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