Question

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 it's fall.)
Use vertical motion model to solve this problem.

Answer 1

h=-16t^2+vt+s
0=-16t^2+(0)t+16. Substitute 0 for h and v, sub 16 for s.
0=-16(t^2-1)
0=-16(t-1)(t+1)

t-1=0. Or. t+1=0
+1 +1 -1 -1
--------- ---------
t=1 t=-1 We can't have negative time so the apple lands on the ground after 1 second.
Hope this helps :)

Answer 2

mmmhhh,
distance that an object falls on earth is governed my
d = 16t^2 , where t is seconds and d is in feet

so 16t^2 = 16
t^2 = 1
t = √1 = 1