Answer:
Decreases by times
Explanation:
The intensity of a sound is defined as the energy of the sound that is flowing in an unit time through the unit area which is in the direction that is perpendicular to the direction of the sound waves movement.
The intensity of energy is described by the inverse square law. It states that the intensity varies inversely with the distance square of the distance.
In other words, the sound intensity decreases as inversely proportional to the squared of the distance. i.e.
In the context when the distance was 3 m, the intensity of the sound was =
But when the distance became 6 cm or 0.06 m, the sound intensity decreases by =
= times
For the work-energy theorem, the work done by the worker must be equal to the variation of mechanical energy of the bucket.
The variation of mechanical energy of the bucket is sum of the variation of potential energy (U) and kinetic energy (K):
Taking the ground as reference, the variation of potential energy of the bucket is:
while the variation of kinetic energy is simply equal to the final kinetic energy of the bucket, since initially it was at rest (so its initial kinetic energy was zero):
So the minimum amount of work that must be done is equal to the variation of mechanical energy of the bucket:
There is a basic difference<span>, because </span>mass<span> is the actual amount of material contained in a body and is </span>measured<span>in kg, gm, etc. Whereas </span>weight<span> is the force exerted by the gravity on that object mg. Note that </span>mass<span> is independent of everything but </span>weight<span> is different on the earth</span>