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Hunter-Best [27]
3 years ago
9

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 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.
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 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.
 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 smallest.
Physics
1 answer:
Reil [10]3 years ago
8 0
The correct option is D.
Sound proofing is usually achieved by using materials that absorbed or reduce sounds. Different materials are used in sounding proofing and these differ in their abilities to absorb or reduce sounds. The coefficient of absorption of a material refers to that material ability to absorb sound. The higher the percentage of a material absorption coefficient, the better the material's ability to absorb sound. Thus, in the question given above, the material with 62% absorption coefficient have the greatest ability of the three materials to absorb sound effectively. <span />
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Answer:

Explanation:

105 km/hr = 29.17 m/s

r = (v²/R) / g

r = (29.17²/8.80) / 9.81

r = 9.85

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3 years ago
What is the potential energy of a 2kg plant that is on a windowsill 1.3 m high?
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25.48

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3 years ago
The vector sum of the forces acting on the beam is zero, and the sum of the moments about the left end of the beam is zero. (a)
Marysya12 [62]

This question is incomplete, the complete question is;

The vector sum of the forces acting on the beam is zero, and the sum of the moments about the left end of the beam is zero.

(a) Determine the forces and and the couple

(b) Determine the sum of the moments about the right end of the beam.

(c) If you represent the 600-N force, the 200-N force, and the 30 N-m couple by a force F acting at the left end of the beam and a couple M, what is F and M?

Answer:

a)

the x-component of the force at A is A_{x} = 0

the y-component of the force at A is A_{y}  = 400 N

the couple acting at A is; M_{A} = 146 N-m

b)

the sum of the momentum about the right end of the beam is;  ∑M_{R}  = 0

c)

the equivalent force acting at the left end is; F = -400J ( N)

the couple acting at the left end is; M = - 146 N-m

Explanation:

Given that;

The sum of the forces acting on the beam is zero ∑f = 0

Sum of the moments about the left end of the beam is also zero ∑M_{L} = 0

Vector force acting at A, F_{A} = A_{x}i + A_{y}j

Now, From the image, we have;

a)

∑f = 0

F_{A} - 600j + 200j = 0i + 0j

A_{x}i + A_{y}j - 600j + 200j = 0i + 0j

A_{x}i + (A_{y} - 400)j = 0i + 0j

now by equating i- coefficients'

A_{x} = 0

so, the x-component of the force at A is A_{x} = 0

also by equating j-coefficient

A_{y} - 400 = 0

A_{y}  = 400 N

hence, the y-component of the force at A is A_{y}  = 400 N

we also have;

∑M_{L} = 0

M_{A}  - ( 30 N-m ) - ( 0.380 m )( 600 N ) + ( 0.560 m )( 200 N ) = 0

M_{A} - 30 N-m - 228 N-m + 112 Nm = 0

M_{A} - 146 N-m = 0

M_{A} = 146 N-m

Therefore, the couple acting at A is; M_{A} = 146 N-m

b)

The sum of the moments about right end of the beam is;

∑M_{R} = (0.180 m)(600N) - (30 N-m) - ( 0.56 m)(A_{y} ) + M_{A}

∑M_{R} = (108  N-m) - (30 N-m) - ( 0.56 m)(400 N ) + 146 N-m

∑M_{R} = (108 N-m) - (30 N-m) - ( 224 N-m ) + 146 N-m

∑M_{R}  = 0

Therefore, the sum of the momentum about the right end of the beam is;  ∑M_{R}  = 0

c)

The 600-N force, the 200-N force and the 30 N-m couple by a force F which is acting at the left end of the beam and a couple M.

The equivalent force at the left end will be;

F = -600j + 200j (N)

F = -400J ( N)

Therefore, the equivalent force acting at the left end is; F = -400J ( N)

Also couple acting at the left end

M = -(30 N-m) + (0.560 m)( 200N) - ( 0.380 m)( 600 N)

M = -(30 N-m) + (112 N-m) - ( 228 N-m))

M = 112 N-m - 258 N-m

M = - 146 N-m

Therefore, the couple acting at the left end is; M = - 146 N-m

7 0
2 years ago
What is the de Broglie wavelength for a proton with energy 50 keV? Due to the limitations of Canvas, please give the wavelength
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Answer:

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\lambda  = \frac{h}{\sqrt{2 m K}}

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m = 1.67 x 10^-27 kg

\lambda  = \frac{6.63 \times  10^{-34}}{\sqrt{2 \times 1.67\times 10^{-27}\times 80\times 10^{-16}}}

λ = 1.2826 x 10^-13 m

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Describe what happens at the molecular level when a substance boils
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When a substance boils the molecules within the substance move faster and farther apart, meaning (depending on the current matter state of the substance) molecules will go into more liquid and gaseous states
solid----> liquid ----> gas 
In the case of something boiling the substance goes from liquid to gas due to the increased molecular activity because to heat...
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3 years ago
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