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arsen [322]
1 year ago
12

An installation consists of a 30-kVA, 3-phase transformer, a 480-volt primary, and a 240-volt secondary. Calculate the largest s

tandard size circuit breaker permitted for primary-only protection to be used without applying Note 1 of Table 450.3(B).
Physics
1 answer:
Nikitich [7]1 year ago
5 0

Answer:  45 A

Explanation:

Primary only protection 3-phase

I =  3 phase kVA / ( 1.723 * V)

I = 30000 / ( 1.732 * 480 ) = 36.085 A

Table 450.3(B)

Currents of 9A or more column

primary only protection  = 125%

Max OCPD pri = 125% of I = 1.25 * 36.085 = 45.11 A

 Table 450.3(B) Note 1   does not apply, use next smaller Table 240.6(A)

Next smaller = 45 A

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What is mightier than steel yet cowers from the sun?
JulijaS [17]

Ice is only thing which is mightier than steel  because it can breaks things which are made up of steels like ships but in the sunlight ice melts away it means it cowards away.

4 0
3 years ago
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Suppose that the net resistance comes from two resistors in series: R=R1+R2. Assume that you measure each resistor independently
rewona [7]

Answer:

± (.021 ) ohm

Explanation:

In the addition of two physical quantities , the uncertainties are simply added .

So , net uncertainty in the value of R will be

± (.007 +.014)

=± (.021 ) ohm

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3 years ago
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When a roller coaster gets to the bottom of a descent, describe the energy transfers and changes to energy stores that happen if
Feliz [49]

Answer:

its B

Explanation:

It's B & A at the same time because A. a roller coaster uses brakes to slow down and stop. B is the most reasonable answer. Because all roller coasters go up and over a second time over the hill, but they also slow down. But go with B.

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6 0
2 years ago
Take the mechanical equivalent of heat as 4 J/cal. A 10-g bullet moving at 2000 m/s plunges
klasskru [66]

Assuming that all the bullet’s energy heats the paraffin, its final temperature is 27.1 degree C. The correct option is D.

<h3>What is temperature?</h3>

Temperature is the degree of hotness and coldness of the material.

The energy of the bullet E = 1/2 mv²

E = 1/2 x 10 x 10⁻³ x (2000)²

E = 2 x 10⁴ J

This heat is used in heating the paraffin

E = m x c ΔT = m x c (Tfinal -Tinitial)

2 x 10⁴ J = 1 x 2.8 x 10³ x (Tfinal -20)

Tfinal = 27.1°C

Thus, the final temperature is 27.1 degree C. The correct option is D.

Learn more about temperature.

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4 0
2 years ago
A particle moving along the x-axis has a position given by m, where t is measured in s. What is the magnitude of the acceleratio
8090 [49]

Question:

A particle moving along the x-axis has a position given by x=(24t - 2.0t³)m, where t is measured in s. What is the magnitude of the acceleration of the particle at the instant when its velocity is zero

Answer:

24 m/s

Explanation:

Given:

x=(24t - 2.0t³)m

First find velocity function v(t):

v(t) = ẋ(t) = 24 - 2*3t²

v(t) = ẋ(t) = 24 - 6t²

Find the acceleration function a(t):

a(t) = Ẍ(t) = V(t) = -6*2t

a(t) = Ẍ(t) = V(t) = -12t

At acceleration = 0, take time as T in velocity function.

0 =v(T) = 24 - 6T²

Solve for T

T = \sqrt{\frac{-24}{6}} = \sqrt{-4} = -2

Substitute -2 for t in acceleration function:

a(t) = a(T) = a(-2) = -12(-2) = 24 m/s

Acceleration = 24m/s

4 0
3 years ago
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