Question

Notes Ask Your T A fireman d-37.0 m away from a burning building directs a stream of water from a ground-level fire hose at an angle of 0 -25.0 above the horizontal as shown in the figure. If the speed of the stream as it leaves the hose is v40.0 m/s, at what height will the stream of water strike the building? 16.2 Your response differs from the correct answer by more than 10%. Double check your calculations, m

Answer 1

reach the buldirg 31 m = 1,02 see

Answer 2

SOLUTION :

Hose at ground level shoots water at an angle of 25º and speed of 40 m/s. 

upward.

So, 

horizontal speed  of water, Vh = 40 cos (25) = 36.252311 m/s

vertical speed  of water , Vv = 40 sin (25) = 16.90473 m/s

Building is 37 m away from the fire hose.

Time needed to reach the building

= Distance / Horizontal Speed 

= 37 / 36.252311

= 1.0206246 sec.

In the vertical direction gravity will decelerate the vertical speed of water

at the deceleration rate of 9.8 m/sec^2 .

So, 

Height achieved in t secs. = u t - 1/2 g t^2  ; (u = Vv)

So, height achieved in 1.0206246 secs. 

= (16.90473)(1.0206246) - 1/2 * 9.8 * (1.0206246)^2

= 12.14918 = 12.15    meters approx. 

Hence, water will hit the 37 meter away building at a height of 12.15 meters approx.

(ANSWER)