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Lady bird [3.3K]
1 year ago
11

Your boss asks you to design a room that can be as soundproof as possible and provides you with three samples of material. The o

nly information on each sample's label is the material's coefficient of absorption. The coefficient of absorption listed on Sample A is 30%, on Sample B is 47%, and on Sample C is 62%. When your boss asks for your choice and the reasoning behind it, what would you tell him?
A. Sample A would be best, because the percentage of the energy in an incident wave that remains in a reflected wave from this material is the smallest.
B. Sample A would be best, because the percentage of the energy in an incident wave that remains in a reflected wave from this material is the largest.
C. Sample C would be best, because the percentage of the energy in an incident wave that remains in a reflected wave from this material is the smallest.
D. Sample C would be best, because the percentage of the energy in an incident wave that remains in a reflected wave from this material is the largest.
Physics
2 answers:
earnstyle [38]1 year ago
4 0

The correct answer is Option C) Sample C would be best, because the percentage of the energy in an incident wave that remains in a reflected wave from this material is the smallest.


As the coefficient of absorption would define the energy present in the reflected wave, the material C has the highest percentage of absorption i.e. 62% and would be best suitable to make a sound proof room.

Alex_Xolod [135]1 year ago
4 0

Answer: Option C: Sample C would be best, because the percentage of the energy in an incident wave that remains in a reflected wave from this material is the smallest.

Explanation:

The absorption coefficient of the samples is given. Sample A has 30%, Sample B has 47% and Sample C has 62%. This means that sample C absorbs the most percentage of energy incident on it. The energy in the reflected wave would be least. Hence, it would be best to use for a room to make it soundproof.


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A projectile of mass m is fired horizontally with an initial speed of v0​ from a height of h above a flat, desert surface. Negle
Grace [21]

Complete question is;

A projectile of mass m is fired horizontally with an initial speed of v0 from a height of h above a flat, desert surface. Neglecting air friction, at the instant before the projectile hits the ground, find the following in terms of m, v0, h and g:

(a) the work done by the force of gravity on the projectile,

(b) the change in kinetic energy of the projectile since it was fired, and

(c) the final kinetic energy of the projectile.

(d) Are any of the answers changed if the initial angle is changed?

Answer:

A) W = mgh

B) ΔKE = mgh

C) K2 = mgh + ½mv_o²

D) No they wouldn't change

Explanation:

We are expressing in terms of m, v0​, h, and g. They are;

m is mass

v0 is initial velocity

h is height of projectile fired

g is acceleration due to gravity

A) Now, the formula for workdone by force of gravity on projectile is;

W = F × h

Now, Force(F) can be expressed as mg since it is force of gravity.

Thus; W = mgh

Now, there is no mention of any angles of being fired because we are just told it was fired horizontally.

Therefore, even if the angle is changed, workdone will not change because the equation doesn't depend on the angle.

B) Change in kinetic energy is simply;

ΔKE = K2 - K1

Where K2 is final kinetic energy and K1 is initial kinetic energy.

However, from conservation of energy, we now that change in kinetic energy = change in potential energy.

Thus;

ΔKE = ΔPE

ΔPE = U2 - U1

U2 is final potential energy = mgh

U1 is initial potential energy = mg(0) = 0. 0 was used as h because at initial point no height had been covered.

Thus;

ΔKE = ΔPE = mgh

Again like a above, the change in kinetic energy will not change because the equation doesn't depend on the angle.

C) As seen in B above,

ΔKE = ΔPE

Thus;

½mv² - ½mv_o² = mgh

Where final kinetic energy, K2 = ½mv²

And initial kinetic energy = ½mv_o²

Thus;

K2 = mgh + ½mv_o²

Similar to a and B above, this will not change even if initial angle is changed

D) All of the answers wouldn't change because their equations don't depend on the angle.

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Formation of an insoluble solid

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One of the remarkable visible signs that indicates a precipitation reaction when two solutions are mixed is the formation of an insoluble solid. The insoluble solid formed is the precipitate.

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Answer:

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tamaranim1 [39]

Answer:

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