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4 years ago

Why are diamonds so good at cutting things answers?

2 answers:

4 0

Diamonds are so good at cutting things, because they are very hard minerals. They can cut other minerals, but other minerals can’t cut them. Out of all the different kinds of minerals on the Mohs’ hardness scale, diamonds rank right at the top, at the hardness of 10. That means, that they are the hardest out of all of the other minerals. The higher the number, the harder it is to be cut.

balu736 [363]4 years ago

3 0

Because they have sharp edges

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A gasoline engine absorbs 2 500 J of heat and performs 1 000 J of mechanical work in each cycle. The efficiency of the engine is

larisa86 [58]

Answer:

The efficiency of the engine is 40 %

Explanation:

Given;

input energy, = 2500 J

output energy, = 1000 J

The efficiency of the engine is given as;

Efficiency = output energy / input energy

Efficiency = 1000 / 2500

Efficiency = 0.4

Efficiency(%) = 0.4 x 100%

Efficiency = 40 %

Therefore, the efficiency of the engine is 40 %

5 0

3 years ago

From hottest to coolest, the order of the spectral types of stars is _________. From hottest to coolest, the order of the spectr

Dimas [21]

Answer:

OBAFGKM

Explanation:

Most stars are classified using the Morgan-Keenan system, which consists of assigning a letter to the star depending on its temperature. The hottest stars are type O, and the coldest stars are type M. As for their color, the coldest stars tend to have red color and the hottest have blue colors.

Within each of these divisions (OBAFGKM), there is another division that are the numbers from 0 to 9: 0 is hotter and 9 colder, to get a better classification of a star.

The order of the letters of the Morgan – Keenan system classification, according to the temperatures is as follows:

O: temperatures greater than 33,000K

B: temperatures between 10,000K and 33,000K

A: temperatures between 7,500K and 10,000K

F: temperatures between 6000K and 7.500K

G: temperatures between 5,200K and 6,000K

K: temperatures between 3,700k and 5,200K

M: temperatures below 3,700 K

6 0

4 years ago

Which of the following is NOT one of Kirchhoff's laws?

Anon25 [30]

Answer:

C) A low-density, cool gas in isolation creates a continuous spectrum.

Explanation:

Kirchhoff’s laws established that:

A solid, liquid or dense incandescent gas emits a continuous spectrum.
A hot and diffuse gas produces bright spectral lines (emission lines).
A gas of lower temperature against a source of continuum spectrum, produces dark spectral lines (absorption lines) superposed in the continuum spectrum.

Stars are perfect examples for Kirchhoff’s laws. Since in the case of the stars, the photons that are received are not directly from the nucleus, but those that have traveled hundreds of thousands of years to reach the stellar atmosphere. Due to the stars are not at homogeneous temperature, density and pressure, but have gradients in different layers because of the nuclear reactions, superficial gravity or to its constant exchange of heat with its surroundings in an attempt to reach the thermodynamic equilibrium, the continuum observed in the stellar spectra comes from the inner layer of the photosphere, while absorption lines are formed in the outer layer of the photosphere and the stellar atmosphere. More accurately, a photon of the inner layer of the photosphere will be absorbed by an electron of an atom or ion that is in the outer layer, generating an electronic transition¹, the electron, upon returning to its base state will emit a photon or a series of photons that will not necessarily go in the same direction of the incident photon, creating an absorption line in the stellar spectrum.

On the other hand, in the case where the stars have surrounding material (diffuse gas), the atoms, molecules or ions in the medium are excited by the radiation that comes from the stellar atmosphere, thus producing an emission spectrum.

Key terms:

¹Electronic transition: When an electron passes from one energy level to another, either for the emission or absorption of a photon.

8 0

3 years ago

A certain electric furnace consumes 24 kw when it is connected to a 240-v line. what is the resistance of the furnace?

weeeeeb [17]

One very handy electrical formula is

Power dissipated by a resistance = (Voltage)²/(resistance) .

24 kilowatts = (240 v)² / Resistance

Multiply each side by (Resistance):

(Resistance) x (24 kilowatts) = (240 v)²

Divide each side by (24 kilowatts):

Resistance = (240 v)² / (24,000 watts)

Resistance = (57,600 / 24,000) (volt² / volt · Amp)

Resistance = 2.4 (volt/Amp)

Resistance = 2.4 Ohms

3 0

4 years ago

An atom of element A has 39 protons. What would the element’s atomic number be?

Maksim231197 [3]

(extra text to be able to submit)

7 0

4 years ago

Read 2 more answers