The prosecution in a robbery trial has hired you as a consultant. The defendant
ID: 1586768 • Letter: T
Question
The prosecution in a robbery trial has hired you as a consultant. The defendant allegedly robbed a bank and to escape the pursuing security guards, took the express elevator to the roof of the building. A witness on the roof recalls seeing the alleged thief throwing a large bag horizontally to a waiting accomplice on the roof of the next building. However, the defence attorney contents that in order to reach the roof of that next building, the defendant would have had to throw the bag with a minimum velocity of 10 m/s and that in a test, the accused could throw the bag with a maximum horizontal velocity of no more than 5 m/s. Find the velocity that the defendant would have had to throw the bag in ordet to reach the roof of that next building. You determine that the bank building is h _ 1 = 260.0 m high, the next building is h _ 2 = 100.0 m high and distance between them is d= 20.0 m .Explanation / Answer
The vertical distance between the roofs of the two buildings is 160 meters.
So, h = vi*t + 0.5*9.8*t^2, and here h = 160 m
now since the bag is thrown horizontally, the initial vertical velocity is 0 m/s.
160 = 0.5*9.8*t^2,
t = sqrt(160/4.9) = 5.71 seconds
the minimum horizontal velocity required for the bag to travel 20 meters.
v = 20/5.71 = 3.50 m/s
Since this velocity is less than 5 m/s. so the accused is GUILTY!
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