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Setler79 [48]
3 years ago
11

calculate minimum number of incident photons per area and of the minimum dose needed to visualize an object of 1 mm squared usin

g x rays of energy 50 keV. ( thickness 10^-3)(contrast 1%)
Physics
1 answer:
Lynna [10]3 years ago
3 0

Answer:

minimum number of photon is 4.05 × 10^{7}

Explanation:

given data

energy = 50 keV = 50 × 10^{3} eV =  50 × 10^{3} × 1.602× 10^{-19}  J

thickness = 10^-3

contrast = 1%

to find out

number of incident photons

solution

we know here equation that is

E  = n  × h  × ν   .......................1

put here all these value

50 × 10^{3} = n × 6.6× 10^{-34} × c/ 1× 10^{-3}

50 × 10^{3} × 1.602× 10^{-19}  = n × 6.6× 10^{-34} ×( 3 × 10^{8} / 1× 10^{-3})

solve it and find n

n = 4.05 × 10^{7}

so here minimum number of photon is 4.05 × 10^{7}

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A loudspeaker located in air generates sound waves of frequency 1,000 Hz. Some of these sound waves enter a pool of water, where
prisoha [69]

Answer:

1.4 m

Explanation:

v = Speed of sound in water = 1400 m/s

f = Frequency of sound = 1000 Hz

\lambda = Wavelength

When we multiply the frequency and the wavelength of a wave we get the velocity of sound in that medium

v=f\lambda\\\Rightarrow \lambda=\dfrac{v}{f}\\\Rightarrow \lambda=\dfrac{1400}{1000}\\\Rightarrow \lambda=1.4\ m

The wavelength of the sound waves in water is 1.4 m

8 0
3 years ago
Salmon often jump waterfalls to reach their
natta225 [31]

Answer:

5.0 m/s

Explanation:

The horizontal motion of the salmon is uniform, so the horizontal component of the salmon's velocity is constant and it is

v_x = u cos \theta

where u is the initial speed and \theta=37.7^{\circ}. The horizontal distance travelled by the salmon is

d=v_x t = (ucos \theta)t

where d = 1.95 m and t is the time needed to reach the final point.

Re-arranging for t,

t=\frac{d}{v_x}=\frac{d}{u cos \theta} (1)

Along the vertical direction, the equation of motion is

y=h+u_y t -\frac{1}{2}gt^2

where:

y = 0.311 m is the final height reached by the salmon

h = 0 is the initial height

u_y = u sin \theta is the vertical component of the initial velocity of the salmon

g=9.81 m/s^2 is the acceleration of gravity

t is the time

Substituting t as found in eq.(1), we get the equation

y=(u sin \theta) \frac{d}{u cos \theta}- \frac{1}{2}g\frac{d^2}{u^2 cos^2 \theta}=d tan \theta - \frac{1}{2}g\frac{d^2}{u^2 cos^2 \theta}

and we can solve this formula for u, the initial speed of the salmon:

y=d tan \theta - \frac{1}{2}g\frac{d^2}{u^2 cos^2 \theta}\\\\u=\sqrt{\frac{gd^2}{2(dtan \theta -y)cos^2 \theta}}=\sqrt{\frac{(9.81)(1.95)^2}{2((1.95)(tan 37.7^{\circ}) -0.311)cos^2 37.7^{\circ}}}=5.0 m/s

5 0
4 years ago
WILL MARK BRAINLIST
ryzh [129]

Answer:

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3 0
2 years ago
The average lifetime of μ-mesons with a speed of 0.95c is measured to be 6 x 10^6 s. Find the average lifetime of μ-mesons in a
Mnenie [13.5K]

Answer:

19.2*10^6 s

Explanation:

The equation for time dilation is:

t = \frac{t'}{\sqrt{1-\frac{v^2}{c^2}}}

Then, if it is observed to have a life of 6*10^6 s, and it travels at 0.95 c:

t = \frac{6*10^6}{\sqrt{1-\frac{(0.95c)^2}{c^2}}} = 19.2*10^6 s

It has a lifetime of 19.2*10^6 s when observed from a frame of reference in which the particle is at rest.

7 0
4 years ago
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