When geologists refer to the "big five," what are they referring to?
the five most important organisms that have become extinct.
the five largest mass extinctions in earth's history.
the five most influential events that have changed the surface of the earth.
the five most important inventions that have allowed scientists to study mass extinctions.

Picture a all traveling at a constant speed around the inside of a circular structure. is the ball accelerating? explain your answer

Each neuron shown in this figure innervates a group of muscle fibers. what is the term for a group of muscle fibers innervated by a single neuron?

Aspring is used to stop a 50-kg package which is moving down a 20º incline. the spring has a constant k = 30 kn/m and is held by cables so that it is initially compressed 50 mm. knowing that the velocity of the package is 2 m/s when it is 8 m from the spring and neglecting friction, determine the maximum additional deformation of the spring in bringing the package to rest.