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3 years ago

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Why is the efficiency of a machine always less than 100%?

1 answer:

never [62]3 years ago

8 0

Answer:The percentage of the work input that becomes work output is the efficiency of a machine. Because there is always some friction, the efficiency of any machine is always less than 100 percent.

Explanation:

Sub to rockingcoolstyle15 on yt

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Which sentence provides evidence that heat travels from Earth’s mantle up to its crust?

olasank [31]

B. Earth’s outer surface is cooler than its interior layers.

Explanation:

The option given above is showing us that the temperature in the interior of the earth is higher than the temperature in the outer layer.
There is travel of heat from the inner core of the earth to the earth's crust. Due to the loss of heat when it reaches the outer layer, there arises a temperature difference.
The heat loss is due to the absorption of heat during its transfer. Hence, option B is the answer.

7 0

3 years ago

When the Glen Canyon hydroelectric power plant in Arizona is running at capacity, 690 m3 of water flows through the dam each sec

igomit [66]

Answer:

The maximum electric power output is $P_{max} =1.339*10^{9} \ W$

Explanation:

From the question we are told that

The capacity of the hydroelectric plant is $\frac{V}{t} = 690 \ m^3 /s$

The level at which water is been released is $h = 220 \ m$

The efficiency is $\eta =$ 0.90

The electric power output is mathematically represented as

$P = \frac{PE_l - PE _o}{t}$

Where $PE_l$ is the potential energy at level h which is mathematically evaluated as

$PE_l = mgh$

and $PE_o$ is the potential energy at ground level which is mathematically evaluated as

$PE_o = mg(0)$

$PE_o = 0$

So

$P = \frac{mgh}{t}$

here $m = V * \rho$

where V is volume and $\rho$ is density of water whose value is $\rho = 1000 kg/m^3$

So

$P = \frac{(\rho * V) * gh}{t}$

$P = \frac{V}{t} * gh \rho$

substituting values

$P =690 * 9.8 * 220 * 1000$

$P =1.488*10^{9} \ W$

The maximum possible electric power output is

$P_{max} = P * \eta$

substituting values

$P_{max} =1.488*10^{9} * 0.90$

$P_{max} =1.339*10^{9} \ W$

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3 years ago

Which SI unit is the correctly abbreviated for describing the mass on an object.

djverab [1.8K]

S.I. Unit of mass is Kilogram which is denoted by Kg

In short, Your Answer would be Option C

Hope this helps!

4 0

3 years ago

Match each word to it's correct meaning.

Ivan

Answer:

fluid transfer of heat by the motion of the particles of gas or fluid

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2 years ago

Read 2 more answers

In the vacuum of outer space, there is no

natta225 [31]

Atmospheric pressure

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3 years ago