A cherry falls from a tree branch that is 9 feet above the ground.a.what is the height of the cherry after 0.2 seconds? ______________b.after how many seconds does the cherry hit the ground?
Accepted Solution
A:
The cinematic equation is: h (t) = (1/2) * a * t ^ 2 + vo * t + h0 Where, a: acceleration vo: initial speed h0: initial height Substituting values: h (t) = (1/2) * (- 32) * t ^ 2 + (0) * t + 9 h (t) = - 16t ^ 2 + 9 For t = 0.2 we have: h (0.2) = - 16 * (0.2) ^ 2 + 9 h (0.2) = 8.36 feet To touch the ground we have: -16t ^ 2 + 9 = 0 16t ^ 2 = 9 t = root (9/16) t = 0.75 s Answer: The height of the cherry after 0.2 seconds is: h (0.2) = 8.36 feet the cherry hits the ground at: t = 0.75 s