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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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A girl (mass M) standing on the edge of a frictionless merry-go-round (radius R, rotational inertia I) that is not moving. She t
vladimir1956 [14]

a) \omega=\frac{-mvR}{I+MR^2}

b) v=\frac{-mvR^2}{I+MR^2}

Explanation:

a)

Since there are no external torques acting on the system, the total angular momentum must remain constant.

At the beginning, the merry-go-round and the girl are at rest, so the initial angular momentum is zero:

L_1=0

Later, after the girl throws the rock, the angular momentum will be:

L_2=(I_M+I_g)\omega +L_r

where:

I is the moment of inertia of the merry-go-round

I_g=MR^2 is the moment of inertia of the girl, where

M is the mass of the girl

R is the distance of the girl from the axis of rotation

\omega is the angular speed of the merry-go-round and the girl

L_r=mvR is the angular momentum of the rock, where

m is the mass of the rock

v is its velocity

Since the total angular momentum is conserved,

L_1=L_2

So we find:

0=(I+I_g)\omega +mvR\\\omega=\frac{-mvR}{I+MR^2}

And the negative sign indicates that the disk rotates in the direction opposite to the motion of the rock.

b)

The linear speed of a body in rotational motion is given by

v=\omega r

where

\omega is the angular speed

r is the distance of the body from the axis of rotation

In this problem, for the girl, we have:

\omega=\frac{-mvR}{I+MR^2} is the angular speed

r=R is the distance of the girl from the axis of rotation

Therefore, her linear speed is:

v=\omega R=\frac{-mvR^2}{I+MR^2}

5 0
2 years ago
The mechanical advantage to simple machines is that they allow a decreased input force to create a larger output force. please s
Rina8888 [55]
<span>The mechanical advantage to simple machines is that they allow a decreased input force to create a larger output force.

<span>TRUE</span></span>
5 0
3 years ago
Bob, Jill, Kim, and Steve measure an object's length, density, mass, and brightness, respectively. Which student must derive a u
netineya [11]
The answer is A. Bob (<span>object's length)

</span>
3 0
2 years ago
What happenes to our body temperature on a cold winter day or a hot summer day
viva [34]

In cold winter day, the body temperature falls down from normal temperature of 98.6°F (37°C) to 95°F (35°C). In winter body losses heat faster than it generates heat. If the temperature fall further below 95°F (35°C), it is emergency condition known as Hypothermia. One has to consult doctor in this case.

In summer hot days, body evaporates water in the form of sweat, in order to remain itself cool. Rise of temperature up to 100°F is normal. It is recommended to hydrate body to maintain temperature in summer days.

3 0
2 years ago
What is the wavelength, in nm, of the line in the hydrogen spectrum when one n value is 3 and the other n value is 6?
iren [92.7K]

Answer:

\lambda=1090nm

Explanation:

Rydberg formula is used to calculate the wavelengths of the spectral lines of many chemical elements. For the hydrogen, is defined as:

\frac{1}{\lambda}=R_H(\frac{1}{n_1^2}-\frac{1}{n_2^2})

Where R_H is the Rydberg constant for hydrogen and n_1, n_2 are the lower energy state and the higher energy state, respectively.

\frac{1}{\lambda}=1.10*10^{7}m^{-1}(\frac{1}{3^2}-\frac{1}{6^2})\\\frac{1}{\lambda}=9.17*10^{5}m^{-1}\\\lambda=\frac{1}{1.09*10^{6}m^{-1}}\\\lambda=1.09*10^{-6}m*\frac{10^{9}nm}{1m}\\\lambda=1090nm

4 0
3 years ago
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