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3 years ago

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Please help fast

1 answer:

Vitek1552 [10]3 years ago

4 0

The balloon could not rise. The air inside would not be an lighters than the air
outside.

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When compared to early vehicles, modern vehicles do not have?

KIM [24]

Modern vehicles do not have steam or coal engines

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3 years ago

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A study of online dating found that when including emoticons in their profiles, response rates for female users _______ by _____

Dvinal [7]

Answer:

Increased, 5%

Explanation:

Recent studies conducted on online dating sites established that the response of female users increased by 5% when emotions are in their profiles even as for male users' response also increased by 8%. Another study also revealed that those who have never used online dating sites and/or mobile dating apps believe that people who use dating apps are desperate.

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3 years ago

An engineer designing a hydroelectric facility recalls that the flow rate (in gallons per second) is four times the value of the

GarryVolchara [31]

Answer:

Flow rate = 86.48 gal/s

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Explanation:

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4 years ago

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Substance Specific Heat (cal/g°C) Specific Heat (J/g°C) water 1.00 4.18 steam 0.96 4.02 alcohol 0.59 2.47 ice 0.50 2.09 wood 0.4

Jobisdone [24]

Answer:

C) 43,2°C

Explanation:

<em>Sensible heat</em> is the amount of thermal energy that is required to change the temperature of an object, the equation for calculating the heat change is given by:

Q=msΔT

where:

Q, heat that has been absorbed or realeased by the substance [J]
m, mass of the substance [g]
s, specific heat capacity [J/g°C]
ΔT, changes in the substance temperature [°C]

To solve the problem, we clear ΔT of the equation and then replace our data:

Q=890 [J],

m=16,6 [g],

s=2,74 [J/g°C]

Q=msΔT.......................ΔT=Q/ms

Δ $T=\frac{890 J}{16,6g*2,47\frac{J}{gC}}=21,7$ °C

As:

ΔT=Tfinal-Tinitial

Tfinal=ΔT+Tinitial

Tfinal=21,7+21,5=43,2°C

The final temperature of the ethanol is 43,2°C.

4 0

4 years ago

Please answer fast. With full step by step solution.

lina2011 [118]

Let <em>f(z)</em> = (4<em>z </em>² + 2<em>z</em>) / (2<em>z </em>² - 3<em>z</em> + 1).

First, carry out the division:

<em>f(z)</em> = 2 + (8<em>z</em> - 2) / (2<em>z </em>² - 3<em>z</em> + 1)

Observe that

2<em>z </em>² - 3<em>z</em> + 1 = (2<em>z</em> - 1) (<em>z</em> - 1)

so you can separate the rational part of <em>f(z)</em> into partial fractions. We have

(8<em>z</em> - 2) / (2<em>z </em>² - 3<em>z</em> + 1) = <em>a</em> / (2<em>z</em> - 1) + <em>b</em> / (<em>z</em> - 1)

8<em>z</em> - 2 = <em>a</em> (<em>z</em> - 1) + <em>b</em> (2<em>z</em> - 1)

8<em>z</em> - 2 = (<em>a</em> + 2<em>b</em>) <em>z</em> - (<em>a</em> + <em>b</em>)

so that <em>a</em> + 2<em>b</em> = 8 and <em>a</em> + <em>b</em> = 2, yielding <em>a</em> = -4 and <em>b</em> = 6.

So we have

<em>f(z)</em> = 2 - 4 / (2<em>z</em> - 1) + 6 / (<em>z</em> - 1)

or

<em>f(z)</em> = 2 - (2/<em>z</em>) (1 / (1 - 1/(2<em>z</em>))) + (6/<em>z</em>) (1 / (1 - 1/<em>z</em>))

Recall that for |<em>z</em>| < 1, we have

$\displaystyle\frac1{1-z}=\sum_{n=0}^\infty z^n$

Replace <em>z</em> with 1/<em>z</em> to get

$\displaystyle\frac1{1-\frac1z}=\sum_{n=0}^\infty z^{-n}$

so that by substitution, we can write

$\displaystyle f(z) = 2 - \frac2z \sum_{n=0}^\infty (2z)^{-n} + \frac6z \sum_{n=0}^\infty z^{-n}$

Now condense <em>f(z)</em> into one series:

$\displaystyle f(z) = 2 - \sum_{n=0}^\infty 2^{-n+1} z^{-(n+1)} + 6 \sum_{n=0}^\infty z^{-n-1}$

$\displaystyle f(z) = 2 - \sum_{n=0}^\infty \left(6+2^{-n+1}\right) z^{-(n+1)}$

$\displaystyle f(z) = 2 - \sum_{n=1}^\infty \left(6+2^{-(n-1)+1}\right) z^{-n}$

$\displaystyle f(z) = 2 - \sum_{n=1}^\infty \left(6+2^{2-n}\right) z^{-n}$

So, the inverse <em>Z</em> transform of <em>f(z)</em> is $\boxed{6+2^{2-n}}$ .

4 0

3 years ago