Question

an object is launched at 4 ft./s from 88 foot tall platform the objects height H in feet after T seconds is given by the equation H=-16T^2+8t+80 when does the object strike the ground

Answer 1

1.5seconds

Explanation:

When the ball hits the ground, the height is equal to zero. So find t when H=0:

H=16t²+8t+80

0=16t²+8t+80

0=2t²+t+10

0=(2t-3)(t+2)

So (2t-3)=0, or (t+2)=0

So t=1.5 or t=-2. Time can't be negative though, so we take our answer as 1.5seconds