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3 years ago

A laser pulse with wavelength 520 nm contains 4.40 mj of energy. how many photons are in the laser pulse?

1 answer:

3 0

Given:
λ = 520 nm = 520 x 10⁻⁹ m, the wavelength
E = 4.4 mJ = 4.4 x 10⁻³ J, energy per packet or pulse

The Planck-Einstein equation is
E = (hc)/λ
where
c = 3 x 10⁸ m/s, the velocity of light

The energy per photon is
e = fh
where
f = c/λ = 3 x 10⁸/520 x 10⁻⁹ = 5.7692 x 10¹⁴ 1/s

The number of photons is
E/e = c/(fλ)
= (3 x 10⁸)/[(5.7692 x 10¹⁴)*(520 x 10⁻⁹)]
= 1

Answer: 1

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A student, starting from rest, slides down a water slide. On the way down, a kinetic frictional force (a nonconservative force)

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The velocity with which the student goes down the bottom of glide is 12.48m/s.

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mass of the student 73 kg

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Substituting values,

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3 years ago

A cart loaded with bricks has a total mass of 22.2 kg and is pulled at constant speed by a rope. The rope is inclined at 27.5 ◦

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Answer:

W = 1.432 KJ

Explanation:

given,

mass = 22.2 Kg

angle of the rope = 27.5°

distance on the ground = 24 m

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acceleration due to gravity, g = 9.8 m/s²

Work done = ?

W = F d cosθ

a = 0 because it is moving with constant speed

equating all the forces acting in x direction

F cosθ = F friction = μN

equating all the forces acting in y direction

F sinθ + N -mg =0

now,

N = mg - F sinθ

putting value of N

F cosθ = μ mg -μ F sinθ

F (cosθ + μsinθ ) = μ mg

$F = \dfrac{\mu mg}{cos\theta + \mu sin\theta}$

$F = \dfrac{0.32 \times 22.2 \times 9.8}{cos 27.5^0+0.32 \times sin27.5^0}$

F =67.28 N

now,

W=F d cosθ

W =67.28 x 24 x cos(27.5)

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0.5-lbm of a saturated vapor is converted to asaturated liquid by being cooled in a weighted piston-cylinder device maintained a

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Answer:

The boiling point temperature of this substance when its pressure is 60 psia is 480.275 R

Explanation:

Given the data in the question;

Using the Clapeyron equation

$(\frac{dP}{dT} )_{sat } = \frac{h_{fg}}{Tv_{fg}}$

$(\frac{dP}{dT} )_{sat } = \frac{\frac{H_{fg}}{m} }{T\frac{V_{fg}}{m} }$

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we substitute

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$T_2$ $= ( 15 + 460 ) + \frac{(60-50)psia(\frac{144in^2}{ft^2}) }{272.98}$

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