Medal!
A firecracker shoots up from a hill 140 feet high, with an initial speed of 100 feet per second. Using the formula H(t) = -16t2 + vt + s, approximately how long will it take the firecracker to hit the ground?

Five seconds
Seven seconds
Nine seconds
11 seconds
I think its seven seconds ?? is that right ?

Question

Medal!
A firecracker shoots up from a hill 140 feet high, with an initial speed of 100 feet per second. Using the formula H(t) = -16t2 + vt + s, approximately how long will it take the firecracker to hit the ground? 

 Five seconds
 Seven seconds
 Nine seconds
 11 seconds
 I think its seven seconds ?? is that right ?

anonymous · Answer

@salmanjalali87  can you help me out ?

 and to others Ill fan too

anonymous · Answer

7.5

anonymous · Answer

so it would be 7 seconds

adamaero · Answer

http://assets.openstudy.com/updates/attachments/546fb7f8e4b0db93229a376d-abhisar-1416610590751-code_of_conduct.pdf#page=2