Please answer the following question completely and correctly. (Please show all

Question

Please answer the following question completely and correctly. (Please show all work & write neatly).

**To receive full credit, make sure you start with a sketch of the situation and list your known and unknown variables. **

A brush fire is burning on a rock ledge on one side of a ravine that is 30m wide A fire truck on the opposite side of the ravine at an elevation 8.5 m above the burning brush. The firehose nozzle is aimed 35o above the horizontal, and the firefighters control the water velocity by adjusting the water pressure. Because the water supply is limited, they want to use as little water as possible. At what speed should the stream of water leave the hose so that the water hits the fire on the first shot. **To receive full credit, make sure you start with a sketch of the situation and list your known and unknown variables. 4.

Explanation / Answer

u = s*cos(35) = 0.819*s

Vi = s*sin(35) = 0.574*s

30 = ut

so t = 30/u = 30/0.819*s = 36.63/s

h = 8.5 = Vi*t - 4.9t^2

8.5 = 0.574 s (36.63 / s) - 4.9 (36.63 / s)^2

8.5 = 21 - 6574.6 /s^2

6574.6 = 12.5 x s^2

s = 22.93 m/s

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