Nitrogen makes up 78% of Earth’s atmosphere. Which statement best describes an important function of the nitrogen cycle? A. Animals breathe in nitrogen gas and their cells use it. B. Bacteria convert nitrogen gas into molecules that plants use. C. Plants use nitrogen gas to make energy during photosynthesis. D. Nitrogen gas combines with oxygen to form water that supports all life.

Review multiple-concept example 7 in this chapter as an aid in solving this problem. in a fast-pitch softball game the pitcher is impressive to watch, as she delivers a pitch by rapidly whirling her arm around so that the ball in her hand moves in a circle. in one instance, the radius of the circle is 0.626 m. at one point on this circle, the ball has an angular acceleration of 66.1 rad/s2 and an angular speed of 12.6 rad/s. (a) find the magnitude of the total acceleration (centripetal plus tangential) of the ball. (b) determine the angle of the total acceleration relative to the radial direction.