Question 442619: Hi,
I have an algebra question that states the following: (not sure where to go with this)
If h = -16t^2 + 48t represents the height of a rocket, in feet, t seconds after it was fired, when will the rocket hit the ground?
It does give a hint: "The rocket is on the ground when h = 0"
So it states that the rocket will hit the ground after _______ second(s).
Found 2 solutions by mananth, ikleyn:
Answer by mananth(16949)   (Show Source):
You can put this solution on YOUR website! At t=0, h=0, it is on ground before firing
h=-16t^2+48
h =0 when it hits the ground after firing
-16t^2+48=0
16t(-t+3)=0
/16
t(-t+3)=0
t= 0 OR t=3
It will hit after 3 seconds
Answer by ikleyn(53427)  (Show Source):
You can put this solution on YOUR website! .
Hi,
I have an algebra question that states the following: (not sure where to go with this)
If h = -16t^2 + 48t represents the height of a rocket, in feet, t seconds after it was fired, when will the rocket hit the ground?
It does give a hint: "The rocket is on the ground when h = 0"
So it states that the rocket will hit the ground after _______ second(s).
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
It is interesting to know how physicists solve such problems.
The problem says that the model rocket was launched from the ground level
with vertical speed of v = 48 feet per second, and the gravity acceleration
is g = 32 ft/s^2.
Then according to kinematic, the time to get the highest point is t =  = 1.5 seconds,
and the same time of 1.5 seconds is needed for the model rocket to fall from the highest point to the ground.
The sum 1.5 + 1.5 = 3 seconds is the time from the starting moment to the moment when
the model rocket hits the ground.
Solved.
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