luis wanted to throw an apple to Kim, who was on a balcony 40 ft abouve him, so he tossed it upward with an initial speed of 56 ft/s. kim missed it on the way up, but then caught it on the way down. how long was the apple in hte air?
2006-10-17 12:52:52 · 3 answers · asked by Amanda 4 in Science & Mathematics ➔ Mathematics
Equation of motion:
h=-16t² ft/s² + 56t ft/s
You want to find the second t where h=40 ft. So:
40 ft=-16t² ft/s² + 56t ft/s
16t² ft/s² - 56t ft/s + 40 ft = 0
Multiply by 1/16 s²/ft:
t² - 7t/2 s + 5/2 s² = 0
t² - 7t/2 s + 49/16 = 9/16 s²
(t-7/4 s)²=9/16 s²
t-7/4 s= ± 3/4 s
t=7/4 s ± 3/4 s
Since we want the second time where it passed the balcony:
t=(7/4+3/4) s = 2.5 seconds
2006-10-17 13:04:14 · answer #1 · answered by Pascal 7 · 0⤊ 0⤋
V = Vo + AT
V = final velocity
Vo = initial velocity
A = acceleration due to gravity
T = Time(which uwant to find)
2006-10-17 20:03:56 · answer #2 · answered by eriknba 2 · 0⤊ 0⤋
time for max ht:
v=0=v_0-32t
t=56/32=1.75s
max ht:
h=v_ot-16t^2=49ft
falling 49-40=9ft
9=16t^2
t^2=9/16
t=.75
total time=1.75+.75=2.5s
2006-10-21 16:38:47 · answer #3 · answered by yupchagee 7 · 0⤊ 0⤋