The "missing" 4 kg may have escaped the scene of the fire in the
form of hot gases, and as particles of soot and ash that were seen
leaving in the form of "smoke".
Answer:
I believe the answer is D
Explanation: The doppler affect isan increase or decrease in the frequency of sound, light, or other waves as the source and observer move toward or away from each other.
The efficiency of the process is 42%
From the question given above, the following data were obtained:
Useful energy = 250 watt
Wasteful energy = 600 watt
<h3>Efficiency =? </h3>
The efficiency of the process can be obtained as illustrated below:

<h3>Efficiency = 42%</h3>
Therefore, the efficiency of the process is 42%
Learn more: brainly.com/question/2300041
I don't understand what you are looking for. I can tell you that the speed of molecules does change during state changing.
Answer:
The new Coulomb force is q₁q₂/9πε₀r²
Explanation
The coulomb force between the two charges q₁ and q₂ at a distance r in air is given by F = q₁q₂/4πε₀r².
Now, let us assume the material of dielectric constant κ = 9 is placed between them on the side of the q₁ charge. The value of its effective charge is now q₃ = q₁/κ at a distance of d = r/2 from the q₂ charge.
Since we have air between q₂ and q₃, the coulomb force between them is
F' = q₂q₃/4πε₀d²
= q₂(q₁/κ)/4πε₀(r/2)²
= 4q₂q₁/κ4πε₀r²
= 4/κ(q₂q₁/4πε₀r²)
= 4/9 × (q₂q₁/4πε₀r²)
= q₁q₂/9πε₀r²
So, the new Coulomb force is q₁q₂/9πε₀r²