John is shot out of a cannon going 300 feet per second, he is 4,000 feet above sea level. How long before he hits the ground?

Question

word problem

Answer 1

There is a lot of information missing from the problem statement.  I am going to assume:

• The cannon is aimed horizontally (no vertical component)
• The John falls from 4000 feet to sea level. 

 

With the first assumption, the speed with which John is moving as he leaves the barrel is irrelevant.  The time he will take to fall 4000 feet is the same time as if he just stepped off of a 4000 foot cliff.  For a constant acceleration (g) we have:

 

      h = (1/2)gt²

      2h/g = t²

      √(2h/g) = t

 

Where h = height = 4000 ft, g = the acceleration due to gravity = 32 ft/sec², and t = time.  Plug in h=4000, g=32 and compute t.