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2 years ago

What were Katherine Johnson publications?

1 answer:

7 0

Answer: 1 Reaching for the Moon : the autobiography of NASA mathematician Katherine 2 Johnson by Katherine G Johnson( Book )

3 Katherine Johnson by Thea Feldman( Book )

4 Katherine Johnson by Ebony Wilkins( Book )

5Counting the stars by Lesa Cline-Ransome( Book )

6An Act to Award Congressional Gold Medals to Katherine Johnson and Dr.

Explanation:

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Some people wish that we lived in a recollapsing universe that would eventually stop expanding and start contracting. For this t

Monica [59]

Answer:

(B) Dark energy does not exist and there is much more matter than current evidence suggests.

Explanation:

The repulsive force which is accelerating expansion of the universe is called as dark energy. Most of matter present in the universe is the dark matter of about eighty five percent.

So, a collapsing universe would not have the dark energy and there is more matter which is not the dark matter. This theory is rejected because expansion of the universe is observable.

4 0

3 years ago

Inez uses hairspray on her hair each morning before going to school. The spray spreads out before reaching her hair partly becau

Tamiku [17]

Answer:

$7.0\cdot 10^{-13}C$

Explanation:

The magnitude of the electrostatic force between two charged objects is

$F=k\frac{q_1 q_2}{r^2}$

where

k is the Coulomb's constant

q1 and q2 are the two charges

r is the separation between the two charges

The force is attractive if the charges have opposite sign and repulsive if the charges have same sign.

In this problem, we have:

$r=0.070 cm =7\cdot 10^{-4} m$ is the distance between the charges

$q_1=q_2=q$ since the charges are identical

$F=9.0\cdot 10^{-9}N$ is the force between the charges

Re-arranging the equation and solving for q, we find the charge on each drop:

$F=\frac{kq^2}{r^2}\\q=\sqrt{\frac{Fr^2}{k}}=\sqrt{\frac{(9.0\cdot 10^{-9})(7\cdot 10^{-4})^2}{8.99\cdot 10^9}}=7.0\cdot 10^{-13}C$

8 0

2 years ago

Infrared radiation has frequencies from 3.0×1011 to 3.0×1014 Hz, whereas the frequency region for microwave radiation is 3.0×108

igor_vitrenko [27]

Answer:

1. The speed of infrared radiation is the same as microwave radiation.

2. The wavelength of infrared radiation is lower than microwave radiation.

Explanation:

1. The speed of infrared radiation is the same as microwave radiation. This is because both infrared radiation and microwave radiation are electromagnetic waves and all electromagnetic waves move at the same speed, the speed of light.

2. Frequency and wavelength has an inverse relationship. This means that the higher the frequency, the lower the wavelength.

Since the frequency range of infrared waves is higher than that of microwaves, the wavelength range of infrared waves is lower than that of microwaves.

We can prove this by using the maximum frequency value of each wave to calculate their corresponding wavelengths.

Speed of light, c, is given as:

c = λf

Where λ is wavelength and f is frequency.

Wavelength is therefore:

λ = c/f

For infrared wave, the maximum frequency is 3 * 10^14 Hz, hence the corresponding wavelength is:

λ = (3 * 10^8) / (3 * 10^14)

λ = 10^(-6) m

For microwave, the maximum frequency is 3 * 10^11 Hz, hence the corresponding wavelength is:

λ = (3 * 10^8) / (3 * 10^11)

λ = 10^(-3) m