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seraphim [82]
3 years ago
7

A power plant burns coal to generate electricity. Suppose that 1000 J of heat (Q) from the coal fire enters a boiler, which is k

ept at a constant temperature of 900 C. That 1000 J is used to boil water in a boiler. The steam from the boiler is used to drive a turbine that creates electricity (work). The excess heat is put into a cooling tower at 5 C.
Carnot efficiency If everything is perfectly efficient,
• What is the maximum efficiency that the plant could operate at?
• How much work could be done starting from that 1000 J?
Physics
1 answer:
balandron [24]3 years ago
5 0

Answer:

The work done will be "763 J". A further explanation is given below.

Explanation:

The given values are:

Q_1=1000 \ J

Temperature,

T_1=900^{\circ} C

i.e,

    =1173

T_2=5^{\circ}C

i.e.,

    =278

As we know,

⇒  \eta =1-\frac{T_2}{T_1}

On substituting the values, we get

⇒     =1-\frac{278}{1173}

⇒     =\frac{1173-278}{1173}

⇒     =\frac{895}{1173}

⇒     =0.763

then,

⇒  W=\eta Q_1

⇒       =0.763\times 1000

⇒       =763 \ J

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When a coil is carrying a current of 25.0 A that is increasing at 145 A/s the induced emf in the coil has magnitude 3.70 mV.
Aleks04 [339]

Answer:

a) 25.5 µH

b) 22.95 mV

Explanation:

Induced emf in a inductor is given by

E = L * di/dt, where

E is the voltage of the circuit

L is the inductance of the circuit

di/dt if the rate of inductance

A

So we have

0.0037 = L * 145

L = 0.0037 / 145

L = 0.0000255

L = 25.5 µH

B

i(t) = 225t²

Recall that

E = L * di/dt, so that

E = 25.5 µH * |225t²|

Differentiating with respect to t, we have

E = 25.5 * 2 * 225t

E = 25.5 * 450t

Solving for t = 2,we get

E = 25.5 * 450(2)

E = 25.5 * 900

E = 22950 µV or

E = 22.95 mV

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3 years ago
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sleet_krkn [62]

Answer:

The xylem distributes water and dissolved minerals upward through the plant, from the roots to the leaves. The phloem carries food downward from the leaves to the roots. Xylem cells constitute the major part of a mature woody stem or root.

Explanation:

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8 0
2 years ago
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A 6.00-kg box is sliding to the right across the horizontal floor of an elevator. The coefficient of kinetic friction between th
kap26 [50]

Answer: Kinetic frictional force = 23.76N

Explanation: Please see the attachments below

7 0
3 years ago
A watermelon is dropped off of a 50 ft bridge, and it explodes upon impact with the ground. How fast was it traveling in mph upo
Drupady [299]

Answer: 56.72 ft/s

Explanation:

Ok, initially we only have potential energy, that is equal to:

U =m*g*h

where g is the gravitational acceleration, m the mass and h the height.

h = 50ft and g = 32.17 ft/s^2

when the watermelon is near the ground, all the potential energy is transformed into kinetic energy, and the kinetic energy can be written as:

K = (1/2)*m*v^2

where v is the velocity.

Then we have:

K = U

m*g*h = (m/2)*v^2

we solve it for v.

v = √(2g*h) = √(2*32.17*50) ft/s = 56.72 ft/s

6 0
3 years ago
Eric has a mass of 70 . He is standing on a scale in an elevator that is accelerating downward at 1.7 . What is the approximate
pychu [463]

Answer:

B)

Explanation:

The value the scale shows is the reaction force to the normal force (they are equal by Newton's 3rd Law) that the scale exerts on Eric.

The forces on Eric are his weight (downward) and this normal force (upward), so we can write the net force over him as (also using Newton's 2nd Law):

F=W-N=ma

which means

N=W-ma=mg-ma=m(g-a)

and for our values this is:

N=mg-ma=(70kg)(9.8m/s^2-1.7m/s^2)=567N

5 0
2 years ago
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