Question

an object is dropped from the window of an apartment in a high rise building reaches the ground in 3 seconds. on which floor the apartment is located if height of each floor is 4 m and window is 1 meter above the ground of that floor?

Answer 1

Answer on Question #42961 – Physics - Mechanics | Kinematics | Dynamics

an object is dropped from the window of an apartment in a high rise building reaches the ground in 3 seconds. on which floor the apartment is located if height of each floor is 4 m and window is 1 meter above the ground of that floor?

Solution:

t = 3s – time of the flight;

h = 4m – height of the one floor;

H = 1m – position of the window above the ground of the floor;

N – number of the floor, from which an object was dropped;

Equation of motion of the object along Y-axis:

$$y: (N - 1) \cdot h + H = \frac {g t ^ {2}}{2}$$ $$N h = \frac {g t ^ {2}}{2} - H + h$$ $$N = \frac {g t ^ {2}}{2 h} - \frac {H}{h} + 1 = \frac {9.8 \frac {m}{s ^ {2}} \cdot (3 \text{ s}) ^ {2}}{2 \cdot 4 m} - \frac {1 m}{4 m} + 1 = 11.78 \approx 12$$

Answer: apartment is located on 12 floor.

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