1. Kevin had a small blue crystal of unknown composition and a large green anhydrous crystal of known composition. He heated both crystals over a laboratory burner. The green crystal did not
give off steam nor did it change physical appearance. The blue crystal, when heated, gave off
water vapor and became a powder. What can you conclude about the blue crystal? Explain.

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.