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LASIK eye surgery uses pulses of laser light to shave off tissue from the cornea, reshaping it. A typical LASIK laser emits a 1.

Fittoniya [83]

Answer:

143 kW

Explanation:

Given that

Diameter of the beam, d = 1 mm

Wavelength of the beam, λ = 193 nm

Time used by the pulse, t = 14 ns

Energy of the pulse, U = 2 mJ

Recall that Power can be mathematically calculated using the relation,

Power = Work Done / Time,

To solve this, we apply the formula

P = U / Δt

P = 2*10^-3 J / 14*10^-9 s

P = 142857 W

P = 143 kW

3 0

3 years ago

Water moves through a constricted pipe in steady, ideal flow. At the

Irina-Kira [14]

A) Speed in the lower section: 0.638 m/s

B) Speed in the higher section: 2.55 m/s

C) Volume flow rate: $1.8\cdot 10^{-3} m^3/s$

Explanation:

A)

To solve the problem, we can use Bernoulli's equation, which states that

$p_1 + \rho g h_1 + \frac{1}{2}\rho v_1^2 = p_2 + \rho g h_2 + \frac{1}{2}\rho v_2^2$

where

$p_1=1.75\cdot 10^4 Pa$ is the pressure in the lower section of the tube

$h_1 = 0$ is the heigth of the lower section

$\rho=1000 kg/m^3$ is the density of water

$g=9.8 m/s^2$ is the acceleration of gravity

$v_1$ is the speed of the water in the lower pipe

$p_2$ is the pressure in the higher section

$h_2 = 0.250 m$ is the height in the higher pipe

$v_2$ is hte speed in the higher section

We can re-write the equation as

$v_1^2-v_2^2=\frac{2(p_2-p_1)+\rho g h_2}{\rho}$ (1)

Also we can use the continuity equation, which state that the volume flow rate is constant:

$A_1 v_1 = A_2 v_2$

where

$A_1 = \pi r_1^2$ is the cross-section of the lower pipe, with

$r_1 = 3.00 cm =0.03 m$ is the radius of the lower pipe (half the diameter)

$A_2 = \pi r_2^2$ is the cross-section of the higher pipe, with

$r_2 = 1.50 cm = 0.015 m$ (radius of the higher pipe)

So we get

$r_1^2 v_1 = r_2^2 v_2$

And so

$v_2 = \frac{r_1^2}{r_2^2}v_1$ (2)

Substituting into (1), we find the speed in the lower section:

$v_1^2-(\frac{r_1^2}{r_2^2})^2v_1^2=\frac{2(p_2-p_1)+\rho g h_2}{\rho}\\v_1=\sqrt{\frac{2(p_2-p_1+\rho g h_2)}{\rho(1-\frac{r_1^4}{r_2^4})}}=0.638 m/s$

B)

Now we can use equation (2) to find the speed in the lower section:

$v_2 = \frac{r_1^2}{r_2^2}v_1$

Substituting

v1 = 0.775 m/s

And the values of the radii, we find:

$v_2=\frac{0.03^2}{0.015^2}(0.638)=2.55 m/s$

C)

The volume flow rate of the water passing through the pipe is given by

$V=Av$

where

A is the cross-sectional area

v is the speed of the water

We can take any point along the pipe since the volume flow rate is constant, so

$r_1=0.03 cm$

$v_1=0.638 m/s$

Therefore, the volume flow rate is

$V=\pi r_1^2 v_1 = \pi (0.03)^2 (0.638)=1.8\cdot 10^{-3} m^3/s$

Learn more about pressure in a liquid:

brainly.com/question/9805263

#LearnwithBrainly

0 0

3 years ago

Yashoda prepares some lime juice on a hot day. She adds 80 g of ice at a temperature of 0°C to 0.32 kg of lime juice. The temper

Vikentia [17]

Answer:

Explanation:

a )

hear energy required to melt 1 g of ice = 340 J ,

hear energy required to melt 80 g of ice = 340 x 80 J = 27220 J .

b ) energy gained by the melted ice ( water at O°C ) = m ct

where m is mass of water , s is specific heat and t is rise in temperature

= 80 x 4.2 x ( 8°C - 0°C)

= 2688 J .

c )

energy lost by lime juice = energy gained by ice and water

= 27220 J + 2688 J .

= 29908 J .

d )

Let specific heat required be S

Heat lost by lime juice = M S T

M is mass of lime juice , S is specific heat , T is decrease in temperature

= 320 g x S x ( 29 - 8 )°C

= 6720 S

For equilibrium

Heat lost = heat gained

6720 S = 29908 J

S = 4.45 J /g °C .

4 0

3 years ago

The equation P^xV^yT^z= constant is Boyle law for what is the values of x,y,z

Setler79 [48]

Answer:

x = 1, y = 1 and z = 0

Explanation:

Given equation;

$P^x V^y T^z = constant$

Boyle's law states that at constant temperature, the volume of a fixed mass of gas is inversely proportional to its pressure.

Mathematically the law is written as;

$PV = constant$

From the given equation, the values of x, y and z that will match this law is calculated as follows;

$P^1 V^1 T^0 = constant\\\\P^1 = P\\\\V^1 = V\\\\T^0 = 1\\\\P \times V \times 1 = PV = constant\\\\Thus, x = 1, \ y = 1 \ \ and \ z = 0$

6 0

3 years ago

When a gas is heated, it absorbs 196 joules of heat from the surroundings. At the same time, the gas expands, doing pressure-vol

timurjin [86]

Answer:

(a) q positive; w negative.

(b) ΔE = -126 J

(c) E and ΔE

Explanation:

(a) Determine whether the amounts of heat (q) and work (w) exchanged should have positive or negative signs. heat (q) positive negative work (w) positive negative

By convention, when the system absorbs heat from the surroundings, its sign is positive, that is, q = 196 J.

By convention, when the system exerts work on the surroundings, its sign is negative, that is, w = -322 J.

(b) Calculate the change in internal energy (ΔE) of the gas. J

The change in internal energy (ΔE) can be calculated using the following expression.

ΔE = q + w

ΔE = 196 J + (-322 J) = -126 J

(c) Determine whether one or more of the following is a state function:

internal energy (E) of a system,

change in internal energy (ΔE) of a system,

heat (q) absorbed or released by a system,

work (w) done on or by a system.

E and ΔE are state functions (they only depend on the states of the gas), whereas q and w depend on the trajectory.

7 0

3 years ago