00:01
Okay, so we have a fire hose, and we know that the diameter is 8 centimeters, and they have a rate that the water is coming out at 12 meters cubed per minute.
00:15
So that's the volume of water coming out per minute.
00:19
So for the diameter, let's go ahead and figure out what the radius is.
00:27
Obviously, that's going to be half of the diameter.
00:29
So four centimeters this will be more useful and then let's change that into units of meters so 0 .04 meters because that's just the standard units you see the volume rate is in meters cube per minute so for to work out in the equations we'll have to have those same units and then let's go ahead and actually right away change this rate into meters cubed per second because again seconds are just more useful when it comes to combining these with other units so that would be meters cube 12 meters cube per minute is multiplied by one minute is 60 seconds so you'd have 12 divided by 60.
01:34
Our minutes cancel out.
01:36
And you get 0 .2 meters cubed per second.
01:47
And we'll use that.
01:49
So we want to know the exit velocity.
01:55
I'm just call it ve.
01:57
And the exit velocity is going to be equal to this volume rate over the area.
02:08
So that's just the area of the hose nozzle.
02:16
So that's just going to be a circle.
02:18
So our area is going to be pi r squared.
02:23
So that's going to be pi times 0 .04 meters squared, right? and then we'll have that volume rate .20 meters cubed per second.
02:45
And that'll end up giving us the right seconds for a velocity.
02:49
And so when you plug that into your calculator, you should get 39 .79 meters per second.
03:03
And that's your velocity that the water's coming out...