Falling object: time before it reaches the ground and its position

[ellyb]

A flowerpot is knocked off a balcony 20.0m above the sidewalk and falls toward an unsuspecting 1.75-m tall man who is standing below. How close to the sidewalk can the flowerpot fall before it is too lat for a warning shouted from the balcony to reach the man in time? Assume the man below requires 0.300s to respond to the warning.
d=1/2gt2
18.25m=4.9t2
1.93s=t for flowerpot to fall
v=d/t
v=343m/s at 20C
343=18.25/t
t=.053s for sound to reach man
So, tflower=tlast instant+tsound+treaction
1.93=.053+.3+t
1.577s=t
okay, d=1/2gt2
d=4.9(1.5772)
12.2m=dCan someone help me i am not sure if i did it right?

 

[Pheo1986]

that seems gd to me. it has fallen 12.2m so it will be 7.8m above the sidewalk

 

[kerimek]

Yes, your calculations are correct. The flowerpot will reach the ground in 1.93 seconds and the sound will take 0.053 seconds to reach the man, leaving him with 1.577 seconds to react. In this time, the flowerpot will fall a distance of 12.2 meters, which is well above the man's height of 1.75 meters. Therefore, if a warning is shouted from the balcony, the man will have enough time to react and avoid being hit by the falling flowerpot.