EXAMPLE 7 = The Path of a Projectile An object thrown or fired straight upward at an initial speed of vo ft/s will reach a height of h feet after t seconds, where h and t are related by the formula h = -1612 + Vot Suppose that a bullet is shot straight upward with an initial speed of 800 ft/s. Its path is shown in Figure 2. (a) When does the bullet fall back to ground level? (b) When does it reach a height of 6400 ft? (c) When does it reach a height of 2 mi? (d) How high is the highest point the bullet reaches?

b(I-n) +0= ,t The water depth in a harbor is 6 m at low tide and 14 m at high tide. One cycle is completed in 12 hours. a) Find the equation for the water depth, d(t) meters, as a function of the time, h hours, after high tide, which occurred at midnight. 240 A miz b) Algebraically find the times when the level of water is 11 meters during the first 12 hours