If an object is dropped from a height of 144 ft, the function h(t) = –16t² + 144 gives the height of the object after t seconds. When will the object hit the ground?

Question

anonymous · Answer

ok

mysesshou · Answer

is this the whole thing?  $$h(t) = -16 t^2 + 144$$  because then t=0, which can't happen if you're dropping it 144ft
a little confused.  :(

anonymous · Answer

yes that is the height of the oblect AFTER t seconds. and the question asks when will the object hit the ground.

mysesshou · Answer

Ah, so perhaps the 144ft is not needed.  The ground is when h=0,  so that works to solve for 
$$0 = -16 t^2 + 144$$ and solve for t  ??

mysesshou · Answer

Do you think that works ?

anonymous · Answer

no find out how many seconds it will take for the object to hit the gorund

anonymous · Answer

do you get it?

anonymous · Answer

nvm i found the answer, its 3 seconds

mysesshou · Answer

sorry I had misunderstood.  So, if it wants when it hits the ground, then I think h=0, giving: 

$$144 = -16 t^2 $$

$$\sqrt{-144/(-16)} = t  = 3 sec$$

Do you think this works?

mysesshou · Answer

Sorry I wasn't much good help   :(

mysesshou · Answer

good for you for finding it  :)

mysesshou · Answer

sorry !