SOLUTION: A model rocket is launched from the roof of a building. Its flight path through the air is modelled by h(t)=-5t2+30t+10, where h(t) is the height of the rocket above the ground in
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Question 1174255: A model rocket is launched from the roof of a building. Its flight path through the air is modelled by h(t)=-5t2+30t+10, where h(t) is the height of the rocket above the ground in metres and t is the time after launch in seconds. I've done all the questions for this question, except these two.
1. How high is this building?
2. When is this rocket 45m of the ground? Answer by ikleyn(52794) (Show Source):
The height of the building is the constant term of the given quadratic function.
Indeed, it is the height, where the "model rocket" starts at t= 0.
Substitute t= 0 into the formula for the height, and you will get h(0) = 10 meters.
Question 1 is just answered.
Question 2
To answer this question, solve this quadratic equation
-5t^2 + 30t + 10 = 45 meters.
You will get two solutions for "t": one works for the rocket moving up, while the other works for falling rocket.
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