SOLUTION: An object is thrown down from the top of a building 1280 feet tall with an initial velocity of 32 feet per second. The distance s (in feet) of the object from the ground after t se

Question 1207823: An object is thrown down from the top of a building 1280 feet tall with an initial velocity of 32 feet per second. The distance s (in feet) of the object from the ground after t seconds is s = 1280- 32t- 16t^2.
(a) When will the object strike ground?
(b) What is the height of the object after 4 seconds?
Found 2 solutions by greenestamps, mananth:
Answer by greenestamps(13196) (Show Source): You can put this solution on YOUR website!

(a) When it strikes the ground, its height is 0:

Reject the negative solution

t = 8

ANSWER: 8 seconds after it is thrown

(b) Substitute t=4 in the given equation

I leave that to you....

ANSWER: 896 feet

Answer by mananth(16946) (Show Source): You can put this solution on YOUR website!
An object is thrown down from the top of a building 1280 feet tall with an initial velocity of 32 feet per second. The distance s (in feet) of the object from the ground after t seconds is s = 1280- 32t- 16t^2.
(a) When will the object strike ground?
(b) What is the height of the object after 4 seconds?
The equation

s=1280- 32t- 16t^2.
When object touches ground s=0
put s=0 and simplfy
t^2+2t-80=0
factorise
(t+10)(t-8)=0
t=-10 or t=8
The object hits the ground after 8 seconds
After 4 seconds
s=1280- 32t- 16t^2.
substitute t=4 and calculate
s=1280- 32*(4)- 16*4^2).=896 feet
The height of the object after 4 seconds is 896 feet.
RELATED QUESTIONS
Hi, I could use some help with this problem. I had thought there was a similar one in... (answered by bucky)
Please help me solve this: A ball is thrown vertically upward from the top of a... (answered by nerdybill)
A ball is thrown vertically upward from the top of a building 144 feet tall with an... (answered by KnightOwlTutor)
An object is thrown upward from the top of a 260 foot tall building with an initial... (answered by solver91311)
an object is thrown upward from the top of a 48-foot building with an initial velocity of (answered by rothauserc)
A ball is thrown vertically upward from the top of a building 128 feet tall with an... (answered by stanbon,solver91311)
A ball is thrown vertically upward from the top of a building 64 feet tall with an... (answered by ikleyn,Boreal)
A ball is thrown vertically upward from the top of a building 112 feet tall with an... (answered by Solver92311)
7) The path of a falling object is given by the function where represents the initial... (answered by stanbon)