Which is true of the amount of matter in ecosystems? a). It decreases over time.
b). It remains constant.
c). Scientists cannot determine how it changes.
d). It increases over time.

Sara goes on a slingshot ride in an amusement park. she is strapped into a spherical ball that has a radius 3*10^2 of centimeters. what is the volume of air in the spherical ball? use this formula: volume of a sphere=4/3pi, r^3 , where r is the sphere’s radius.