Answer:
Herd immunity
Explanation:
Herd immunity refers to the resistance of a group of people against infection and the spread of a pathogen. It occurs when a high proportion of the members of that group are resistant against a particular pathogenic infection. When an earlier exposure or vaccination of a large proportion of individuals of a population does not allow the pathogen to spread among and infect the otherwise susceptible members of the population, the population is said to have acquired the herd immunity.
In the given example, vaccination of a large percentage of a population protected the susceptible individuals against a particular microbe. This represents an example of herd immunity.
Answer: The ball's velocity will increase
When a ball falls below the point of releasing its velocity increases. The falling of the ball is controlled by the two forces, the drag force and acceleration due to gravity. The acceleration due to gravity accelerates the ball in the downward direction at the constant rate. The drag force slows the ball when it falls below and it is a function of velocity so when the velocity of the ball increases so the drag force also increases.
