SOLUTION: a fualty firworks rocket is launched vertically with an initial velocity of 124ft/s and then falls to the earth unexploded. Its height h in feet after t seconds is given by h(t)=

Question 289650: a fualty firworks rocket is launched vertically with an initial velocity of 124ft/s and then falls to the earth unexploded. Its height h in feet after t seconds is given by h(t)= -16(Tsquared) + 124T. During which time interval after launch will the height of the rocket exceed 100 feet.
Answer by jsmallt9(3758) (Show Source): You can put this solution on YOUR website!

It might help to look at the graph:
}
From this we can see that there is a continuous set of times where the rocket is over 100 feet. The rocket will be higher than 100 feet just after it first reaches 100 feet high and it will stay over 100 until the height is 100 feet high for a second time. To find this interval of time we just have to find the times when the rocket is 100 feet:

Since this is a quadratic equation we will start by getting one side of the equation equal to zero. Adding to and subtrcacting 124t from each side we get:

Next we'll factor:

Since the second factor does not factor any further, we'll resort to using the Quadratic Formula:

So the rocket is over 100 feet between
seconds
and
seconds.

RELATED QUESTIONS
3. A model rocket is launched from the ground with an initial velocity of 352 ft/sec. e. (answered by ikleyn)

A model rocket is launched from the ground with an initial velocity of 160 feet/second.... (answered by jim_thompson5910)

A rocket is launched from atop a 101 - foot cliff with an initial velocity of 116... (answered by Alan3354)

Suppose a model rocket is launched from a platform 2 ft above the ground with an initial... (answered by Boreal)

Can anyone help me? An experimental rocket is launched into the air from ground level... (answered by ewatrrr)

An expreimental rocket is launched into the air from ground level with the Earth with an... (answered by ewatrrr)

a rocket is launched from atop a 32-foot cliff with an initial velocity of 154 ft/s.... (answered by venugopalramana)

If a rocket is launched vertically upward from ground level with an initial velocity of... (answered by CubeyThePenguin)