A bird sitting 16 feet above the ground in an apple tree dislodges an apple.after how many seconds does the apple land on the ground? (assume no branches interfere with its fall)

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lfryerda | High School Teacher | (Level 2) Educator

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Since the apple is 16 feet above the ground, we can use the equation of motion for constant gravity to solve for time:

`h=1/2g t^2+v_0t+h_0`  where `v_0=0` is the initial speed, and `h_0=16` is the initial height.  Also, the final height is h=0.  This gives

`0=1/2(-32)t^2+16`   simplify multiplication

`0=-16t^2+16`   move variable to left side

`16t^2=16`   divide by 16

`t^2=1`   take square roots

`t=+-1`   need positive root for time


It takes 1 second for the apple to fall to the ground.