A fireman, 54.6 m away from a burning
building, directs a stream jet of water from
a ground level fire hose at an angle of 38.2 degrees above the horizontal.

If the speed of the stream as it leaves the
hose is 38.1 m/s, at what height will the
stream of water strike the building? The
acceleration due to gravity is 9.8 m/s^2.

Question

A fireman, 54.6 m away from a burning
building, directs a stream jet of water from
a ground level fire hose at an angle of 38.2 degrees above the horizontal.

If the speed of the stream as it leaves the
hose is 38.1 m/s, at what height will the
stream of water strike the building? The
acceleration due to gravity is 9.8 m/s^2.

anonymous · Answer

Correct answer: 26.6714 m.

anonymous · Answer

I'm thinking the first thing to do is look at the horizontal motion
We have enough information to work out the time taken to travel from hose to building
Then we can use that time to calculate the vertical displacement

anonymous · Answer

I found the time (1.824 second), but how do I find the y displacement?

anonymous · Answer

I tried two equations but they both didn't work because I think I assumed that is hit the wall at the highest part of the parabola

anonymous · Answer

just use y = Vy(0)t - gt^2/2

anonymous · Answer

where did you get that formula from? Is it derived or just one of the ones you memorized? I am slving for Vyo at the moment...

anonymous · Answer

it's one of the standard equations for uniformly accelerated motion in a straight line

anonymous · Answer

$$s(t)=s(0)+ut+\frac{ 1 }{ 2 }at^2$$

anonymous · Answer

hmm, I got a wrong answer, could you try and plug it in too? I got 23.6 m/s for the velocity in the y direction...

anonymous · Answer

y component of velocity would be 38.1sin38.2
i get 23.56

anonymous · Answer

never mind I just put it in wrong...

anonymous · Answer

looks right to me

anonymous · Answer

I got it, I just read the equation wrong, so all is well! Thanks again!

anonymous · Answer

ok : )