A projectile is thrown from the top of a building with an initial velocity of 30 m/s in the horizontal direction. If the top of the building is 30 m above the ground, how fast will the projectile be moving just before it strikes the ground?
1) 35 m/s
2) 39 m/s
3) 31 m/s
4) 43 m/s
5) 54 m/s
Answer: 2