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vekshin1
3 years ago
8

What is the basic definition of a black hole?

Physics
1 answer:
polet [3.4K]3 years ago
8 0

Explanation:

Black holes are the most massive and dense objects in the whole universe. They are peculiar objects. The gravity near black hole is so strong that even light can not escape it. That is why the name: Black hole. It is formed after the death of a supermassive star. All the mass of the star is condensed in to a very small area having a very string gravity. Imagine the Sun squeezed in to an object of diameter of just 3 km!

You can define it as a dead super massive star from which nothing can escape.

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A machinist with normal vision has a near point at 25 cm. The machinist wears eyeglasses in order to do close work. The power of
Alik [6]

Answer:

17.4 cm

Explanation:

Power of lens = +1.75 diopters

Focal length of lens

f=\frac{100}{1.75}=\frac{400}{7}

This is a convex lens as focal the diopter given is positive which makes the focal length positive. Image distance will be negative.

v = -25

\frac{1}{v}-\frac{1}{u}=\frac{1}{f}\\\Rightarrow \frac{1}{-25}-\frac{1}{u}=\frac{1}{\frac{400}{7}}\\\Rightarrow -\frac{1}{u}=\frac{7}{400}+\frac{1}{25}\\\Rightarrow \frac{1}{u}=-\frac{7}{400}-\frac{1}{25}\\\Rightarrow \frac{1}{u}=-0.0575\\\Rightarrow u=-17.4\ cm

∴ The new near point is 17.4 cm

7 0
3 years ago
Identify the type of chemical reaction that is described.
Anastasy [175]

Water breaks down into  hydrogen and oxygen: It is a decomposition reaction as a single substance decomposes to give two products.

H_2O \rightarrow H_2 +\frac {1}{2}O_2

Leaves make starch using  chlorophyll and carbon dioxide: Synthesis reaction: as the synthesis reaction involves two or more than two reactants which join together to result into a single main product along with the formation of simple by products.

6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2

Food burns in oxygen gas  and releases a lot of energy: Combustion: Combustion process involves the use of oxygen to give products along with release of energy.

C_6H_{12}O_6 + 6O_2\rightarrow 6CO_2 + 6H_2O

Adding vinegar (acid) to baking soda (alkali) gives  a product that is neither  acidic nor alkaline: Neutralization: acetic acid in vinegar reacts with soda (base) to give salt (neutral) and .

CH_3COOH + NaHCO_3\rightarrow CH_3COONa +H_2O + CO_2





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Answer:

B

Explanation:

8 0
3 years ago
Read 2 more answers
The valency of oxygen is 2​
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Answer:

Yes the valency of oxygen is 2

5 0
3 years ago
Help I don’t understand this question
7nadin3 [17]
Metals
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