Question

An explosion causes debris to rise vertically. the formula h=-16t^2+48t describes the height of the debris above the ground, h, in feet, t seconds after the explosion. when will the debris be 32 feet above the ground?

Answer 1

To get the result we have to subsitute h=32 to given equation and solve it.
32=-16t^2+48t /-32
0=-16t^2+48t-32 /*(-1)
0=16t^2-48t+32 /:4
4t^2-12t+8=0 /:4
t^2-3t+2=0
Now we can use delta
delta=b^2-4ac
delta=9-4*2=1
x1=
`(3-1)/(2)=1`
x2=
`(3+1)/(2)=2`
The answer is 1 second and 2 second (when hover and falling down)