The intensity ratio at point A and B will be 81:16.
<u>Explanation:</u>
Sound waves are known to get faded with increase in the distance. This is because, the intensity of the sound is inversely proportional to the square of the distance of the source from the observer. So, if an observer is standing greater distance from the source of the sound, he/she will find difficulty in hearing the sound.
So, as the distance between the source and observer increases, the intensity of the sound wave decreases.

As here two points A and B are located at 4 m and 9 m distance from the source, then the intensity of sound at A and B will be inversely proportional to their respective square of the distance as shown below.

Similarly,

So, the ratio of intensity at point A and B will be

Thus, the intensity ratio at point A and B will be 81:16.
Complete question:
A 0.50 kilogram frog is at rest on the bank surrounding a pond of water. As the frog leaps from the bank, the magnitude of the acceleration of the frog is 4.0 meters per second^2. Calculate The magnitude of the net force exerted on the frog as it leaps.
Answer:
2.0N
Explanation:
Given that,
Mass, m of the frog = 0.5 kg
The acceleration of the frog = 4.0 m/s².
We have been asked To find,
The magnitude of the net force exerted on the frog as it leaps.
So
We calculate this using the formula below :
F = ma
When we insert the values into the formula, we have:
F = 0.5 kg × 4 m/s²
F = 2.0 N
Therefore, the magnitude of net force is 2.0 N.
The correct answer is I disagree. Elements form all pure substances, but some pure substances include elements bonded together to form molecules and compounds.
Elements are pure substances but these elements also make other things such as water. The water molecule is made of two elements called oxygen and Hydrogen. Now water itself is a pure substance as it is chemically bonded hydrogen and Oxygen but it is composed of more than one element
The amount of friction depends on the force pushing the surfaces together. If this force increases, the hills and valleys of the surfaces can come into closer contact. The close contact increases the friction between the surfaces.
I think it’s A but i might be wrong