Question 1057940: When firefighters fight a grass fire, they prefer to stand back from the edge of the fire and "lob" the water from the hose onto the fire. The stream of water is under high pressure, and the water can be airborne for some period of time. If the spray of the water leaving the hose is modelled by the equation d = - 1.5 t2 + 60, where d represents the distance (in metres) between the hose and the fire and t represents the time (in seconds) elapsed since the water was sprayed (at a constant high pressure), determine how long the water remains in the air after leaving the nozzle. Round the answer to 3 significant digits.
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! When firefighters fight a grass fire, they prefer to stand back from the edge of the fire and "lob" the water from the hose onto the fire. The stream of water is under high pressure, and the water can be airborne for some period of time. If the spray of the water leaving the hose is modelled by the equation
d = - 1.5t^2 + 60, where d represents the distance (in metres) between the hose and the fire and t represents the time (in seconds) elapsed since the water was sprayed (at a constant high pressure), determine how long the water remains in the air after leaving the nozzle. Round the answer to 3 significant digits.
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Find d > 0
-1.5t^2 + 60 > 0
1.5t^2 < 60
t^2 < 40
t < 2*sqrt(10) = 6.325 seconds
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Cheers,
Stan H.
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