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4 years ago

What is Dark Matter?

Physics

1 answer:

AveGali [126]4 years ago

5 0

Explanation:

dark matter is a form of matter thought to account for approximately 85% of the matter in the universe and about a quarter of its total mass–energy density or about 2.241×10⁻²⁷ kg/m³. Its presence is implied in a variety of astrophysical observations, including gravitational effects that cannot be explained by accepted theories of gravity unless more matter is present than can be seen. For this reason, most experts think that dark matter is abundant in the universe and that it has had a strong influence on its structure and evolution. Dark matter is called dark because it does not appear to interact with the electromagnetic field, which means it doesn't absorb, reflect or emit electromagnetic radiation, and is therefore difficult to detect.

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Usually the force of gravity on electrons is neglected. To see why, we can compare the force of the Earth’s gravity on an electr

miv72 [106K]

Answer:

$6.4\cdot 10^{-15} N$

Explanation:

The electric force exerted on the electron is given by:

$F=qE$

where

$q=1.6\cdot 10^{-19}C$ is the magnitude of the electron charge

E = 40000 V/m is the electric field

Substituting,

$F=(1.6\cdot 10^{-19} C)(40000 V/m)=6.4\cdot 10^{-15} N$

By comparison, the gravitational force exerted on the electron is:

$F=mg$

where

$m=9.10939\cdot 10^{-31} kg$ is the mass of the electron

g = 9.8 m/s^2 is the acceleration due to gravity

Substituting,

$F=(9.10939\cdot 10^{-31} kg)(9.8 m/s^2)=8.93\cdot 10^{-30}N$

6 0

4 years ago

A thunderstorm starts to form when water evaporates to form clouds. Which of the following best explains why thunderstorms usual

Morgarella [4.7K]

Thunderstorms might form on warm days simply because heat is what causes evaporation, causing rain. Thunderstorms also form when the atmosphere is unstable! Meaning the hot air is above the cold air, evaporation occurs, it rains, and then rapid expansion of heat in the air caused by lighting causes thunder.

5 0

4 years ago

A car travels 2,000 mi at a<br> constant speed of 70 mi/hr.<br> How long did the trip take?

ella [17]

Answer:

<h2>28.57 hours</h2>

Explanation:

The time taken can be found by using the formula

$t = \frac{d}{v} \\$

d is the distance

v is the velocity

From the question we have

$t = \frac{2000}{70} = \frac{200}{7} \\ = 28.571428 ...$

We have the final answer as

<h3>28.57 hours</h3>

Hope this helps you

5 0

3 years ago

Read 2 more answers

When a liquid is introduced into the air space between the lens and the plate in a Newton's-rings apparatus, the diameter of the

Leviafan [203]

Answer:

$n_l=1.58$

Explanation:

Newton's ring equation relates the initial and final diameter of the ring, to the index of refraction of the air and the index of refraction of the liquid between the lens and the plates, as follows:

$n_ld_f^2=n_ad_i^2$