For which of these would the special theory of relativity be most important?
a. the space shuttle orbiting earth
b. a collision between two large trucks on a highway
c. the eruption of a large volcano after many earthquakes
d. experiments performed in high-speed particle accelerators

Emmy kicks a soccer ball up at an angle of 45° over a level field. she watches the ball's trajectory and notices that it lands, two seconds after being kicked, about 20 m away to the north. assume that air resistance is negligible, and plot the horizontal and vertical components of the ball's velocity as a function of time. consider only the time that the ball is in the air, after being kicked but before landing. take "north" and "up" as the positive ‑ and ‑directions, respectively, and use ≈10 m/s2 for the downward acceleration due to gravity.