Mission Impossible: Special agent Ethan Huny tries to escape an assassin by jump
ID: 2278359 • Letter: M
Question
Mission Impossible: Special agent Ethan Huny tries to escape an assassin by jumping horizontally off a flat roof. His goal is to reach a window, two stories or 5.15 m down, on the building across the alley.
Ignore air resistance.
If the alley is 11.9 m wide, how fast must he run when jumping off the roof?
(Start from the basic equations. Clearly state all known quantities. Then show the individual steps of your work. Always show the equation before substituting numbers. Always use units with numbers. Just the right answer will not give full credit.)
Explanation / Answer
First find the time it takes to fall 5.15m:
d = vi + 1/2at^2
d = vi + 1/2at^2
5.15 = 0 + 1/2(9.81)t^2
t^2 = ((2)(5.15)) / (9.81)
t = 1.02467 seconds
Next you find how how fast you must be going to jump 11.9m in 1.02467 seconds (the time it takes you to fall 5.15m):
d = vi * t
11.9 = vi * 1.02467
vi = 11.9 / 1.02467
vi = 11.613 m/s
He must jump off the roof running at 11.613m/s