Answer:
When the velocity of an object changes it is said to be accelerating. Acceleration is the rate of change of velocity with time. ... Acceleration occurs anytime an object's speed increases or decreases, or it changes direction.
So that we do not contaminate it with microorganisms or garbage or other human stuff.
Answer:

Explanation:
In a uniform circular motion, since a complete revolution represents 2π radians, the angular velocity, which is defined as the angle rotated by a unit of time, is given by:

Here T is the period, that is, the time taken to complete onee revolution:

Replacing (2) in (1):

Compressions are the areas of high pressure while rarefractions are low pressure area
The environmental changes can will negatively affect different organisms differently, for example some organisms might die due to failure of the organisms to adapt to the new changes. Some organisms will be forced to migrate in order to counter these changes, this may lead to this organisms leaving their old living routine and adapt to the new methods of living, this may lead to evolution caused by new environment.