The height of a ball after t seconds is given by h=80t-16t^2. How long did it take the ball to hit the ground?

Question

The height of a ball after t seconds is given by h=80t-16t^2.  How long did it take the ball to hit the ground?

amistre64 · Answer

when does h=0?

amistre64 · Answer

factor it out:

16t(5-t)

anonymous · Answer

dont know it doesnt say. i copied the question exactly

amistre64 · Answer

we know that anything times zero = 0; so either 16t = 0  or  5-t =0

amistre64 · Answer

when t=0 that makes no sense, so it can be disregarded as a false positive;  lets go with t=5 and see where that gets us

anonymous · Answer

so we mulity 5 x 5= 25 then 25 x 16

amistre64 · Answer

h = 80(5) - 16(5)2

0 = 400 - 16(25)

0 = 400 - 400 .... looking like a possibility

anonymous · Answer

sorry i am lost if it is correct would the answer b 0 or 400

amistre64 · Answer

if the ball is dropped from a certain height, then t=0 makes no sense; but if we are starting the ball at ground level, and throwing it up, then maybe t=0 is an option

anonymous · Answer

ok i get that

amistre64 · Answer

Since it does not state that we "drop" the ball, itd be safe to include 0 id assume.

amistre64 · Answer

at any rate; 5 seconds is what it takes after being "released" to hit the ground

anonymous · Answer

k thank you