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4 years ago

A machine can never be 100% efficient because some work is always lost due to what?

2 answers:

8 0

A machine can never be 100% efficient because some work is always lost due to the lack of materials or equipment that would convert work by 100%. It follows the second law of entropy. The ideal engine is known as Carnot’s engine having a 100% efficiency. So far, no engine has ever gotten to 100%.

kari74 [83]4 years ago

8 0

Answer:

Friction

Explanation:

Ik cuz i took tha test, i wouldn't lie to fellow students <3

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A thin Nichrome wire connected to an ammeter surrounds a region of time-varying magnetic flux, and the ammeter reads 13 amperes.

Semenov [28]

Answer:

The current would be same in both situation.

Explanation:

Given that,

Current I = 13 A

Number of turns = 23

We need to calculate the induced emf

Using formula of induced emf is

$\epsilon=NA\dfrac{dB}{dt}$

For N = 1

$\epsilon=A\dfrac{dB}{dt}$

We need to calculate the current

Using formula of current

$i=\dfrac{\epsilon}{R}$

Put the value of emf

$i=\dfrac{A\dfrac{dB}{dt}}{R}$

Now, if the number of turn is 22 , then induced emf would be

$\epsilon'=NA\dfrac{dB}{dt}$

Then the current would be

$i'=\dfrac{\epsilon'}{NR}$

$i'=\dfrac{NA\dfrac{dB}{dt}}{NR}$

$i'=\dfrac{A\dfrac{dB}{dt}}{R}$

$i'=i$

Hence, The current would be same in both situation.

4 0

3 years ago

When a potential difference of 10 V is placed across a certain solid cylindrical resistor, the current through it is 2 A. If the

Keith_Richards [23]

Answer:

New Resistance = 0.5556 ohm

Explanation:

Resistance = resistivity * length /area

Here since resistivity and length are constant, we only need to see how the resistance increases or decreases with change in area.

New Area = pi * (3*D)^2 / 4

Old Area = pi * D^2 / 4

The ratio of new area / old area is :

$\frac{New Area}{Old Area} = 9$

Since area increases 9 times, and it is inversely proportional to resistance:

Resistance decreases by 9 times.

So, old resistance = Voltage / Current = 10 / 2 = 5 ohm

New Resistance = 5 / 9 = 0.5556 ohm (decreases by 9 times)

8 0

3 years ago

Explain why the same side of the moon is always facing Earth.

Ad libitum [116K]

Answer:

The moon keeps the same face pointing towards the Earth because its rate of spin is tidally locked so that it is synchronized with its rate of revolution (the time needed to complete one orbit). In other words, the moon rotates exactly once every time it circles the Earth.

7 0

3 years ago

The temperature of a 700.96 gram piece of metal falls 120⁰C and in the process releases 2001 Joules of energy. What is the speci

olga nikolaevna [1]

Answer:

The specific heat for the metal is 0.466 J/g°C.

Explanation:

Given,

Q = 1120 Joules

mass = 12 grams

T₁ = 100°C

T₂ = 300°C

The specific heat for the metal can be calculated by using the formula

Q = (mass) (ΔT) (Cp)

ΔT = T₂ - T₁ = 300°C - 100°C = 200°C

Substituting values,

1120 = (12)(200)(Cp)

Cp = 0.466 J/g°C.

Therefore, specific heat of the metal is 0.466 J/g°C.

8 0

3 years ago

Which model best represents a pattern?

balandron [24]

The water cycle because <span>the cycle of processes by which water circulates between the earth's oceans, atmosphere, and land, involving precipitation as rain.

it is like a pattern

hope that was helpful.</span>

3 0

3 years ago

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