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Bond [772]
3 years ago
14

When scientists first started mapping human genes, they estimated that there were about 2 million genes. By the late 1990s, it w

as thought that there were only 100,000 genes, and then that number shrank to 19,000 in 2001. Most scientists now believe that humans have about 21,000 genes.
Which statement describes these estimates?

They became more accurate over time.
They became less accurate over time.
They were more accurate and then less accurate.
The accuracy remained the same.
Physics
2 answers:
ICE Princess25 [194]3 years ago
8 0

Answer:

I have the options on e2020. So first, we can definitely mark out D because no way did they stay the same over time. We can cross out B because as scientist "upgrade" over the years, their work will become MORE accurate. Not LESS accurate. So then we are left with A and C. We can cross out C because its doesn't really become accurate and less accurate over time. Then we are left with A which is our answer because scientist can only become more accurate as time goes by with all the new technology advancements they're making.

Hope this helped!! :D (please read whole thing so you understand)

Explanation:

Solnce55 [7]3 years ago
4 0

Answer:

a

Explanation:

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In a double slit experiment, the distance between the slits is 0.2 mm and the distance to the screen is 100 cm. What is the phas
Anni [7]

Answer:

The phase difference is  \Delta \phi  = 180^o

Explanation:

From the question we are told that

     The distance between the slits is d = 0.2 \ mm = \frac{0.2}{1000}  = 0.2 *10^{-3} \ m

     The distance to the screen is D = 100 cm = \frac{100}{100} = 1 \ m

      The wavelength is  \lambda = 400nm

 The distance of the wave from the  central maximum is L =  5mm = 5*10^{-3} m

   

Generally the path difference of this  waves is mathematically represented as

              y = d sin \theta

Here \theta is the angle between the the line connecting the mid-point of the slits with  the screen and the line  connecting the mid-point of the slits to the central maximum

  This implies that

              tan \theta  = \frac{L}{D}

     =>     \theta = tan ^{-1} \frac{L}{D}

             \theta = tan ^{-1} [\frac{5*10^{-3}}{1}]

           \theta =0.2865

Substituting values into the formula for path difference

       y = 0.2 *10^{-3} sin(0.2864)  

       y = 9.997*10^{-7} \ m  

The phase difference is mathematically represented as

          \Delta \phi = \frac{2 \pi }{\lambda }  * y

Substituting values        

         \Delta \phi = \frac{2 \pi }{400 *10^{-9} }  \ * 9.997*10^{-7}

         \Delta \phi =5 \pi

Converting to degree

         \Delta \phi =5 \pi radians = 5 (180^o)  =  180^o  

the solution is subtracted by 360° in order to get the actual angle

 

             

4 0
3 years ago
The pulley shown in the attached diagram has a diameter of 30 centimeters and a mass of 19 kilograms. The pulley is a solid disk
aleksandrvk [35]

Answer:

Explanation:

a) I = ½mR² = ½(19)(0.15²) = 0.21375 kg•m²

b) τ = Fnet(r) = (25 - 12)(0.15) = 1.95 N•m

c) CCW

d) a = τ/I = 1.95 / 0.21375 = 9.12280701... = 9.1 rad/s²

e) CCW

4 0
2 years ago
A harmonic wave on a string with a mass per unit length of 0.050 kg/m and a tension of 60 N has an amplitude of 5.0 cm. Each sec
Dennis_Churaev [7]

Answer:

Power of the string wave will be equal to 5.464 watt

Explanation:

We have given mass per unit length is 0.050 kg/m

Tension in the string T = 60 N

Amplitude of the wave A = 5 cm = 0.05 m

Frequency f = 8 Hz

So angular frequency \omega =2\pi f=2\times 3.14\times 8=50.24rad/sec

Velocity of the string wave is equal to v=\sqrt{\frac{T}{\mu }}=\sqrt{\frac{60}{0.050}}=34.641m/sec

Power of wave propagation is equal to P=\frac{1}{2}\mu \omega ^2vA^2=\frac{1}{2}\times 0.050\times 50.24^2\times 34.641\times 0.05^2=5.464watt

So power of the wave will be equal to 5.464 watt

6 0
2 years ago
A string that is 3.6 m long is tied between two posts and plucked. The string produces a wave that has a frequency of 320 Hz and
marin [14]

To solve this problem it is necessary to apply the concepts related to wavelength depending on the frequency and speed. Mathematically, the wavelength can be expressed as

\lambda = \frac{v}{f}

Where,

v = Velocity

f = Frequency,

Our values are given as

L = 3.6m

v= 192m/s

f= 320Hz

Replacing we have that

\lambda = \frac{192}{320}

\lambda = 0.6m

The total number of 'wavelengths' that will be in the string will be subject to the total length over the size of each of these undulations, that is,

N = \frac{L}{\lambda}

N = \frac{3.6}{0.6}

N = 6

Therefore the number of wavelengths of the wave fit on the string is 6.

5 0
2 years ago
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