Answer:
Since there is attraction force between two charges so the other charge must be - 3C
Explanation:
As we know that the force between two charges is given by formula
here we know that
also we know that
r = 8 cm
now we have
so we have
To solve this problem we will apply the principles of energy conservation. On the one hand we have that the work done by the non-conservative force is equivalent to -30J while the work done by the conservative force is 50J.
This leads to the direct conclusion that the resulting energy is 20J.
The conservative force is linked to the movement caused by the sum of the two energies, therefore there is an increase in kinetic energy. The decrease in the mechanical energy of the system is directly due to the loss given by the non-conservative force, therefore there is a decrease in mechanical energy.
Therefore the correct answer is A. Kintetic energy increases and mechanical energy decreases.
Sound intensity is inversely proportional to the square of the distance between the source and the receiver.
That is
I = k/r^2
where
k = constant
r = radius
When r=1, the intensity is I₁ = k/1 = k
When r=3, the intensity I₂ = k/3² = k/9
Therefore
I₂ = I₁ /9
In decibels,
I = 10 log₁₀(I/I₀)
where I₀ = reference intensity
When r=1,
10 log₁₀ (I₁/I₀) = 270
When r =3,
10 log₁₀ (I₂/I₀) = 10 log₁₀ [(I₂/I₁)*(I₁/I₀)]
= 10 log₁₀ [(1/9)*(I₁/I₀)]
= 10 log₁₀(1/9) + 270
= 260.5
Answer: 260.5 dB (nearest tenth)
