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weeeeeb [17]
3 years ago
6

A fire hose sends 2429 gallons of water per minute against a burning building. The water strikes the building at 66 m/s and does

not bounce back. There are 3.785 L/gal Liters in a gallon, and the density of water is 1 kg/L.
a) What is the magnitude of the rate of change of momentum of the water? Answer in units of N.
b) The rate of change of momentum of the water 1. is negative. 2. cannot be determined. or 3. is positive?
c ) What force does the water exert on the building in 1.2 minutes? Answer in units of N.
Physics
1 answer:
Anastasy [175]3 years ago
5 0

Answer:

a)   Δp = - 10113.2 Kg m / s, b) he rate of change is negative, c)    F = 140.46N

Explanation:

a) For this part let's analyze a water particle, it has a velocity of 66 m / s and when it collides with the building its velocity changes to zero, so the change in moment is

           Δp = mv_f - m v₀

           Δp = -m v₀                              (1)

the change of the moment in a second is

           

if 2429 gallons arrive in in minute (60s) in a second how many gallons arrive      

            c_agua = 2429/60

            c_water = 40,483 gallon/ s

let's use the concept of density to find the mass

            ρ = m / V

            m = ρ V

let's reduce gallons to liters

             c_water = 40,483 gal (3,785 l / 1 gal) = 153.23 l

           

            m = 1 153.23

            m 153.23 kg

           

we substitute in 1

            Δp = - 153.23 66

            Δp = - 10113.2 Kg m / s

b) From the previous result the rate of change is negative

c) Let's use the impulse ratio

             I = f t = Δp

             F t = Δp

               

              F = Δp / t

              F = \frac{10113.2}{1.2 \ 60}

              F = 140.46 N

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pashok25 [27]

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-- There are no horizontal forces that we're aware of acting on the object.  So it maintains the same horizontal velocity for the rest of the story.  It's 10.5m away from the table in (10.5 m) / (7.8 m/s) = 1.35 second .

-- Vertically, it's just an object dropped from 17.6m off the floor.  Shockingly, the distance it falls in time 'T' is (1/2 g) T².  In 1.35 second, that's 8.88 meters ! . . . only about halfway to the floor !

-- In order to fall 17.6 m to the floor, it would need 1.89 seconds.  In <u>that</u> length of time, however, it would travel (7.8 m/s) x (1.89 s) = 14.78 m away from the base of the table.

So you see, either . . .

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OR . . .

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We often see questions posted on Brainly with not enough given information, OR with some information given that's not needed because it's not involved the answer.  

THIS one is different, and it's unusual.  In this one, we have<em> too much</em> given information, we can't ignore any of it because it's all related, but it's inconsistent and it CAN't all be true.

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astra-53 [7]

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I think

D : Hydrogen gas has two atom , and oxygen has one atom

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1. Who first published the classification of the elements that is the basis of our periodic table today?
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3 years ago
Two 10 kg pucks head straight towards each other with velocities of 10 m/s and -20 m/s. They collide and stick together. Calcula
RUDIKE [14]

The final velocity of the two pucks is -5 m/s

Explanation:

We can solve the problem by using the law of conservation of momentum.

In fact, in absence of external force, the total momentum of the two pucks before and after the collision must be conserved - so we can write:

m_1 u_1 + m_2 u_2 = (m_1 +m_2)v

where

m_1 = m_2 = m = 10 kg is the mass of each puck

u_1 = 10 m/s is the initial velocity of the 1st puck

u_2 = -20 m/s is the initial velocity of the 2nd puck

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Re-arranging the equation and solving for v, we find:

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Learn more about momentum:

brainly.com/question/7973509

brainly.com/question/6573742

brainly.com/question/2370982

brainly.com/question/9484203

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3 years ago
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Answer:

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We know that

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Substitute r=0 ,U(0)=0

0=0+C

C=0

Substitute the value

U(r)=-\frac{Gm_Emr^2}{2R^3_E}

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