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A flower pot falls from a balcony of an apartment building in Salem, Oregon and injures a person. Your job is to determine the apartment from which it originated. Video footage from the second floor indicates that it traveled past a 4.000 meter high window in 0.2600 seconds. All floors in the building are 4.000 meters high. From which floor was the flower pot dropped

User Cani
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1 Answer

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Answer:

The pot was dropped from the fourth floor.

Step-by-step explanation:

The height and velocity of the pot is given by the following equations:

y = y0 + v0 · t + 1/2 · g · t²

v = v0 + g · t

Where:

y = height at time "t".

y0 = initial height.

v0 = initial velocity.

t = time.

g = acceleration due to gravity.

v = velocity at time "t".

Let´s place the origin of the frame of reference on the ground. We know that from the second floor (y = 8.000 m) the pot traveled 4.000 m in 0.2600 s. Then:

y = y0 + v0 · t + 1/2 · g · t²

4.000 m = 8.000 m + v0 · 0.2600 s - 1/2 · 9.8 m/s² · (0.2600 s)²

(4.000 m + 1/2 · 9.8 m/s² · (0.2600 s)² - 8.000 m) / 0.2600 s = v0

v0 = -14.11 m/s

This velocity is the velocity of the pot when it is at a height of 8.000 m (on the second floor).

Now let´s find how much time it took the pot to reach that velocity starting from rest (the pot was dropped, not thrown. Then v0 = 0).

v = v0 + g · t

-14.11 m/s = 0 - 9.8 m/s² · t

t = -14.11 m/s / - 9.8 m/s²

t = 1.440 s.

This is the time it takes the pot to reach the second floor (y = 8.000 m). So, let´s calculate y0 using the equation of height:

y = y0 + v0 · t + 1/2 · g · t² (v0 = 0)

8.000 m = y0 - 1/2 · 9.8 m/s² · (1.440 s)²

8.000 + 1/2 · 9.8 m/s² · (1.440 s)² = y0

y0 = 18.16 m

The pot was dropped from (18.16 m / 4 = 4.54 ) the fourth floor.