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Tom [10]
3 years ago
6

The laser pointer emits light because electrons in the material are excited (by a battery) from their ground state to an upper e

xcited state. When the electrons return to the ground state, they lose the excess energy in the form of 520-nm photons. What is the energy gap between the ground state and excited state in the laser material
Physics
1 answer:
ololo11 [35]3 years ago
8 0

Answer:

Explanation:

the energy gap between the ground state and excited state in the laser material will be equal to energy of photons emitted

Wave length of photons = 520 nm

Energy = 1244 / 520 e V ( Formula for conversion of wavelength in nm to energy in eV )

=   2.4  e V

 the energy gap between the ground state and excited state in the laser material  =   2.4  e V

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What is the efficiency of the<br> machine if the input is 263 J and<br> the output is 142 J?
Papessa [141]

Answer: 57.79%

Explanation: 152J/263J=.577946768 or 57.79% or roundedthe nearest whole percent is 58%

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A 1-kilogram turtle crawls in a straight line at a speed of 0.01 m/sec what is the turtles momentum
Arada [10]

Momentum = (mass) x (speed) = (1 kg) x (0.01 m/s)  =  0.01 kg-m/s

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A spherical gas-storage tank with an inside diameter of 9 m is being constructed to store gas under an internal pressure of 1.50
lutik1710 [3]

Answer: 33 mm

Explanation:

Given

Diameter of the tank, d = 9 m, so that, radius = d/2 = 9/2 = 4.5 m

Internal pressure of gas, P(i) = 1.5 MPa

Yield strength of steel, P(y) = 340 MPa

Factor of safety = 0.3

Allowable stress = 340 * 0.3 = 102 MPa

σ = pr / 2t, where

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r = radius of the tank

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t = 0.033 m

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3 years ago
A pin fin of uniform, cross-sectional area is fabricated of an aluminum alloy (k = 160 W/m-K). The fin diameter is D = 4 mm, and
frozen [14]

Answer:

Given that

D= 4 mm

K = 160 W/m-K

h=h = 220 W/m²-K

ηf = 0.65

We know that

m=\sqrt{\dfrac{hP}{KA}}

For circular fin

m=\sqrt{\dfrac{4h}{KD}}

m=\sqrt{\dfrac{4\times 220}{160\times 0.004}}

m = 37.08

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By solving above equation we get

L= 36.18 mm

The effectiveness for circular fin given as

\varepsilon =\dfrac{2\ tanhmL}{\sqrt{\dfrac{hD}{K}}}

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5 0
3 years ago
Read 2 more answers
At one instant, the center of mass of a system of two particles is located on the x-axis at 2.0 cm and has a velocity of (5.0 m/
Nata [24]

Answer:

Explanation:

Given that,

At one instant,

Center of mass is at 2m

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And velocity =5•i m/s

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And it is at rest at position X2= 8m

a. Center of mass is given as

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2 = (0+ 0.8) /(M1 + 0.1)

Cross multiply

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M1 = 0.6/2

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b. Total momentum, this is an inelastic collision and it momentum after collision is given as

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P = (0.3+0.1)×5•i

P = 0.4 × 5•i

P = 2 •i kgm/s

c. Velocity of particle at origin

Using conversation of momentum

Momentum before collision is equal to momentum after collision

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We are told that M2 is initially at rest, then, V2=0

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We already got P(after) = 2 •i kgm/s in part b of the question

Then,

P(before) = P(after)

0.3V1 = 2 •i

V1 = 2/0.3 •i

V1 = 6 ⅔ •i m/s

V1 = 6.667 •i m/s

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