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2 years ago

Is saliva breaking a down a piece of bread chemical or physical

Physics

2 answers:

Elza [17]2 years ago

8 0

It's a chemical change since it cannot be reversed and the saliva releases a new substance

Vlad1618 [11]2 years ago

5 0

Chemical because saliva has a acid type substance in it

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Imagine a ringing bell set inside a sealed glass jar. Once all the air is removed and a vacuum is crated, the ringing sound is n

kenny6666 [7]

working...

Sound wave needs medium to travel

as energy which travels in this wave is because of transfer from one particle to another particle

If there is no medium then energy can not be transferred and sound wave will not travel

so in vacuum we can not listen sound

similarly here air is removed it means there is no medium inside the jar to travel the sound and hence we can not hear it

Option B is correct

Without air, the sound waves cannot travel to the ear.

5 0

3 years ago

Two objects of the same size are both perfect blackbodies. One has a temperature of 3000 K, so its frequency of maximum emission

bija089 [108]

Answer:

a) The colder body (3000k), b) hearter body c) 12000K body

Explanation:

This exercise should know the power emitted by the objects and the distribution of this emission in the energy spectrum, for this we will use Stefan's laws and that of Wien's displacement

Stefan's Law P = σ A e T⁴

Wien displacement law λ T = 2,898 10⁻³ m K

Let's calculate the power emitted for each object.

As they are perfect black bodies e = 1, they also indicate that they have the same area

T = 3000K

P₁ = σ A T₁⁴

T = 12000K

P₂ = σ A T₂⁴

P₂ / P₁ = T₂⁴ / T₁⁴

P₂ / P₁ = (12000/3000)⁴

P₂ / P₁ = 256

This indicates that the hottest body emission is 256 times the coldest body emission.

Let's calculate the maximum emission wavelength

Body 1

T = 3000K

λ T = 2,898 10-3

λ₁ = 2.89810-3 / T

λ₁ = 2,898 10-3 / 3000

λ₁ = 0.966 10-6 m

λ₁ = 966 nm

T = 12000K

λ₂ = 2,898 10-3 / 12000

λ₂ = 0.2415 10-6 m

λ₂ = 214 nm

a) The colder body (3000k) emits more light in the infrared, since the emission of the hot body is at a minimum (emission tail)

b) The two bodies have emission in this region, the body of 3000K in the part of rise of the emission and the body to 12000K in the descent of the emission even when this body emits 256 times more than the other, so this body should have the highest broadcast in this area

c) The emission of the hottest 12000K body is mainly in UV

d) The hottest body emits more energy in UV and visible

e) No body has greater emission in all zones

5 0

3 years ago

Summarize: Based on what you have learned, how will the sound that the observer hears

Reil [10]

Answer: The sound will change due to changes in frequency and the wavelength of the airplane.

Explanation: Let assume that the observer is at a stationary position. The wavelength of the sound from the airplane reduces and the frequency increases as the plane is moving toward the observer. As the airplane passes by, that is, moving away from the observer, the frequency starts to reduce while the wavelength of the sound starts to increase.

The sound that the observer hears will change base on the illustration above.

3 0

2 years ago

How to derive the fourth equation of motion?

Leya [2.2K]

Answer:

To derive the fourth equation of motion, first we have to consider the equation for acceleration and then to rearrange it. or v2 = u2 + 2as and this equation of motion can be used to find the final velocity or the distance travelled if the other values are given.

Explanation:

v= u + at

s =( u + v ) t /2

s = ut + at2/2

v2 = u2 + 2as

6 0

2 years ago

What was significant about the clay samples from the Western Hemisphere? How was the Alvarez hypothesis modified in response?

Elenna [48]

Answer:

Either Answer you Put is fine i put one as an answer and the other is the sample response and got it right.

My Answer: rather than typical sea floor rock, which had been shocked, melted, and ejected to the surface in minutes, and evidence of colossal seawater movement directly afterwards from sand deposits. Crucially the cores also showed a near complete absence of gypsum, a sulfate-containing rock, which would have been vaporized and dispersed as an aerosol into the atmosphere, confirming the presence of a probable link between the impact and global longer-term effects on the climate and food chain.

Sample Response:

Samples from the Western Hemisphere contained significantly higher amounts of shock-fractured quartz. This led Walter and Luis Alvarez to hypothesize that the asteroid impact site was in the Western Hemisphere.

Explanation:

8 0

3 years ago