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 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.
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 largest.
D. 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.
Answer: The correct answer is Option C.
Explanation: For a room to be soundproof, there should be minimum reflection of the sound waves and maximum absorption of the waves.
According to the question, the coefficient of absorption is maximum for Sample C. So, this sample will reflect minimum waves and will absorb maximum waves.
Hence, this sample is the best for making the room soundproof. Hence, the correct answer is Option C.
b. Which of the following statements is true?
A) The average kinetic energy of the ice in cup A is less than that in cup
b.
B)The average kinetic energy of the ice in cup A is greater than that cup in
b.
C)The average kinetic energy of the ice cup A is equal to that in cup
b.
D)The average kinetic energies of the ice in cup A and the ice in cup B are not comparable.
Average kinetic energy is given by the formula:
KE(average) = 3/2*k*T
where k = Boltzmann constant = 1.38*10⁻²³ J/K
T = temperature in Kelvin (K)
Thus, the average KE is dependent only on temperature and independent of mass.
Since the temp in Cup A and B remains the same, the average KE will also be the same.
Ans C)
b)it involves heating charcoal to high tempuratures
c)it involves drawing copper into long wires
d)it involves breaking molecular bonds between copper compounds
The correct answer is D:
it involves breaking molecular bonds between copper compounds .
The explanation :
-when we melt a copper it is a physical change because the substance is still copper and have the same shape.
- but for example Burning a copper it is a chemical change. Fire activates a chemical reaction between copper and oxygen.
-The oxygen in the air reacts with the copper and the chemical bonds are broken.
- the chemical change is changing the other compound bonded to the copper atoms.
So, the correct answer is D
The correct answer for above statement is:
Prices don’t show the total cost of reconstruction fuels to each of us personally or to the community as a whole. Remembered as externalities, the unknown costs of fossil fuels aren’t described in their business price, notwithstanding severe consequences on our health and environment.
Concerns over a global dependence on fossil fuels include environmental, economic, and social consequences.
The statement about “Concerns over a global dependence on fossil fuels include environmental, economic, and social consequences” is true. The environmental, economic, and social consequences greatly affects the global dependence.