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3 years ago

7

What elements are dull,brittle and poor conductors

1 answer:

Artemon [7]3 years ago

8 0

Answer:

I think the answer is Nonmetal...

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A science teacher tells her class that their final project requires students to measure a specific variable and determine the ve

iogann1982 [59]

Answer:

Yes

Explanation:

The velocity measured by Jennifer and Johnny is

$v_m = 34.87 m/s$

The actual velocity is

$v=34.15 m/s$

We can calculate the % error of the students measurement as follows:

$Err = \frac{v_m - v}{v}\cdot 100 = \frac{34.87 m/s-34.15 m/s}{34.15 m/s}\cdot 100 =0.021 \cdot 100 = 2.1 \%$

Which is lower than the 2.5% maximum error required, so the two students will pass the test.

4 0

3 years ago

*help FAST* !15 pts!

Ludmilka [50]

I believe a but none sound like they’d build a laser

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3 years ago

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A composite load consists of three loads connected in parallel. One draws 100 W at a PF of 0.92 lagging, another takes 250 W at

fenix001 [56]

Answer:

a) $I_{RMS} = 4.79 A$

b) $PF = 0.908$

Explanation:

Get the reactive powers for each of the loads:

Reactive power = Real Power * tanθ

For load 1

Active power, P₁ = 100 W

Power factor, $cos \theta_{1} = 0.92$

$\theta_{1} = cos^{-1} 0.92\\\theta_{1} = 23.074$

$Q_{1}= P_{1} tan \theta_{1} \\Q_{1}= 100tan 23.074\\Q_{1}= 42.60 W$

For load 2

Active power, P₂ = 250 W

Power factor, $cos \theta_{2} = 0.8$

$\theta_{2} = cos^{-1} 0.8\\\theta_{2} = 36.87$

$Q_{2}= P_{1} tan \theta_{2} \\Q_{2}= 250tan 36.87\\Q_{2}= 187.5 W$

For load 3

Active power, P₃ = 250 W

Power factor, $cos \theta_{3} = 1$

$\theta_{3} = cos^{-1} 1\\\theta_{3} =0$

$Q_{2}= P_{1} tan \theta_{3} \\Q_{3}= 150tan 0\\Q_{3}= 0 W$

Calculate the total reactive power, $Q_{net} = 42.6 + 187.5 + 0$

$Q_{net} = 230.1 W$

Calculate the total active power, $P_{net} = 100 + 250 + 150 = 500 W$

$S_{net} = P_{net} + Q_{net} \\S_{net} = 500 + j230.1$

$P_{net} = IVcos \theta_{net}$

$\theta_{net} = tan^{-1} \frac{230.1}{500} \\\theta_{net} = 24.712$

V = 115 $V_{rms}$

$500 = I_{RMS} * 115 cos 24.712\\I_{RMS} = 500/104.47\\ I_{RMS} = 4.79 A$

b) Power factor of the composite load is $cos\theta_{net}$

$\theta_{net} = 24.712\\PF = cos 24.712\\PF = 0.908$

4 0

3 years ago

Compared to a stationary galaxy, light from a galaxy that is moving away from earth will appear _____.

Vlad1618 [11]

"B" When an object moves away from us, the light is shifted to the red end of the spectrum, as its wavelengths get longer.

3 0

3 years ago

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HEY CAN ANYONE PLS ANSWER DIS!!!!

Vika [28.1K]

Answer:

hope this helps have a great day!

Explanation:

6 0

4 years ago

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