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3 years ago

Which best summarizes the scientific process that led to our current understanding of DNA? Please help

Physics

2 answers:

solniwko [45]3 years ago

7 0

The answer is B.)

This is because for years scientists have build up and found discoveries that led to recent discoveries brought by previous scientists.

Hope this helps

Fynjy0 [20]3 years ago

3 0

Answer:

The correct answer will be option-B.

Explanation:

The information about DNA we know today form what, structure and functional aspects is the result of the contributions of the discoveries made by the scientists in the past.

The story of DNA begins with the identification of molecule by Johann Friedrich Miescher in the 1860s, identification of its monomers by Albrecht Kossel in 1881, functional role as the genetic material of the organism by the experiments of Hershey and Chase in 1928 and the double-helical model by Watson and Crick shows in 1953 and many other related discoveries by other scientists shows us that new discoveries are made on the basis of work of the other scientists which live or lived in the past.

Thus, Option-B is the correct answer.

The history of the discovery of DNA as genetic material of the organisms konwn to us today statred in 19th century when

Johann Friedrich Miescher

1860s

Chromosomes were first observed in plant cells by Swiss botanist Karl Wilhelm von Nägeli in 1842,

Felice Fontana discovered the nucleolus in eel cells in the year 1774

Hershey-Chase experiment shows that DNA

James Watson & Francis Crick suggest the first correct double-helix model of DNA structure

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Answer: 0.455 m/s^2

Explanation:

f = ma = m x 9.8=689 (the mass is constant)

m = 78.3

now on the elevator

f = 721 = m x a

a= 10.26

the elevator is moving down because there is a increase in weight. the acceleration of elevator = 10.26-9.8 = 0.455

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3 years ago

The pedals on a bicycle give a mechanical advantage by allowing you to turn the pedals a __________ distance to turn the _______

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Short distance to turn the circumference of the wheels. Mechanical advantage is load/effort I think

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3 years ago

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you measured the torque caused by the gyroscope's weight by lifting up the end of the gyroscope (at 7.5 inches). If you measured

DIA [1.3K]

Answer:

i) No, the spring scale does not read a different value

ii) The torque will read a different value, it will reduce

iii) The spring scale does not need to be measured at the center of mass location.

Explanation:

The torque caused by the gyroscope can be given by the relation,

$\tau =$ r × f

$\tau = rf cos \theta$

The torque measured by the gyroscope varies directly with the distance, r.

A decrease in the distance r will also cause a decrease in the value of the torque measured. When the distance, r is reduced from 7.5 inches to 5 inches, the torque caused by the gyroscope's weight also reduces.

The weight of the gyroscope remains constant despite the reduction in the distance because the weight of the gyroscope is not a function of the distance from the gyroscope. Therefore, the spring scale will not read a different value.

Yes, the spring scale does not need to be measured from the center of mass location because the weight does not depend on the location of measurement. The reading of the sprig scale remains constant.

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3 years ago

Suppose that the moment of inertia of a skater with arms out and one leg extended is 3.0 kg⋅m2 and for arms and legs in is 0.90

babymother [125]

Answer:

Her angular speed (in rev/s) when her arms and one leg open outward is $1.56\frac{rev}{s}$

Explanation:

Initial moment of inertia when arms and legs in is $I_i=0.90 kg.m^{2}$

Final moment of inertia when her arms and on leg open outward, $I_f=3.0 kg.m^{2}$

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Let the final angular speed be $w_f$

Since external torque on her is zero so we can apply conservation of angular momentum

$\therefore L_f=L_i$

=> $I_fw_f=I_iw_i$

=> $w_f=\frac{I_iw_i}{I_f}=\frac{0.9\times5.2 }{3.0}\frac{rev}{s}=1.56\frac{rev}{s}$

Thus her angular speed (in rev/s) when her arms and one leg open outward is $1.56\frac{rev}{s}$

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3 years ago

A stationary, 32 kilogram ice skater catches a 0.5 kilogram snowball thrown at a speed of 45 meters per second. The collision is

Pie

Answer:

V = 0.69 m/s

Explanation:

Given that,

The mass of a ice skater, m₁ = 32 kg

The initial speed of the ice skater, u₁ = 0

Mass of a snowball, m₂ = 0.5 kg

The initial speed of a snowball, u₂ = 45 m/s

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$m_1u_1+m_2u_2=(m_1+m_2)V\\\\V=\dfrac{m_1u_1+m_2u_2}{m_1+m_2}\\\\V=\dfrac{32\times 0+0.5\times 45}{32+0.5}\\\\V=0.69\ m/s$

So, the common speed is equal to 0.69 m/s.

4 0

3 years ago