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2 years ago

A 60-Hz 3-phase induction motor is required to drive a load at approximately 850 rpm. How many poles should the motor have

Engineering

1 answer:

Anastaziya [24]2 years ago

7 0

Answer:

8 poles

Explanation:

Given

$Frequency, f = 60Hz$

$Speed, n_s = 850rpm$

Required

Calculate the number of poles the motor should have?

To solve this question, we make use of synchronous angular velocity formula

$n_s = \frac{120f}{P}$

Where

$P = Number\ of\ Poles$

Substitute values for $n_s$ and f in $n_s = \frac{120f}{P}$

$850 = \frac{120 * 60}{P}$

$850 = \frac{7200}{P}$

Multiply both sides by P

$P * 850 = \frac{7200}{P} * P$

$P * 850 = 7200$

Divide both sides by 850

$\frac{P * 850}{850} = \frac{7200}{850}$

$P = \frac{7200}{850}$

$P = 8.47058823529$

However, the number of poles must be an integer.

So:

$P = 8$

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Answer:

The correct answer is option 'B': Load is far from fulcrum and the effort is applied near the fulcrum

Explanation:

A lever works on the principle of balancing of torques. The torque about the fulcrum by the load should be equal to the torque by the applied effort. Since we know that the torque is proportional to both the force and the distance it is applied from the distance from the axis of rotation. A lever is used when we need to lift a heavy load by utilizing this effect of the lever arm.

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Answer:

At first the graphic designer has to break the process down into it's fundamental components. Which could be:

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5) Finalization

6) Revision and Further Corrections

7) Submissions

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Explanation:

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3 years ago

A westbound section of freeway currently has three 12-ft wide lanes, a 6-ft right shoulder, and no ramps within 3 miles upstream

Tresset [83]

Answer:

•Estimated density = 39.685Pc/mi/en

•Level of service, LOS frequency = LOSC

Explanation:

We are given:

•Freeway current lane width,B = 12ft

• freeway current shoulder width,b = 6ft

• percentage of heavy vehicle, Ptb = 10℅

• peak hour factor, PHF = 0.9

Let's consider,

•Number of lanes N = 4

• flow of traffic V = 7500vph

• percentage of Rv = 0, therefore the freeflow speed in freeway FFS = 70mph

• cars equivalent for recreational purpose Er= 2

•cars to be used for trucks and busses Etb= 2.5

Let's first calculate for the heavy adjustment factor.

We have:

$F_H_v = \frac{1}{1+P_t_b(E_t_b-1)+Pr(Er-1)}$

Substituting figures in the equation we have:

$= \frac{1}{1+0.1(2.5-1)+0(2-1)}$

= 0.75

Let's now calculate equivalent flow rate of the car using:

$Vp = \frac{V}{(P_H_F)*N)*(F_H_v)*(F_p)}$

$= \frac{7500}{0.9*4*0.75*1}$

= 2777.7 pc/h/en

Calculating for traffic density, we have:

$D = \frac{Vp}{FFS}$

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3 years ago

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2 years ago

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Write multiple if statements: If carYear is before 1967, print "Probably has few safety features." (without quotes). If after 19

Free_Kalibri [48]

Answer:

The solution code is written in Python 3.

carYear = 1995
if(carYear < 1967):
print("Probably has few safety features.\n")
if(carYear > 1970):
print("Probably has head rests. \n")
if(carYear > 1991):
print("Probably has electronic stability control.\n")
if(carYear > 2002):
print("Probably has airbags. \n")

Explanation:

Firstly, create a variable, carYear to hold the value of year of the car make. (Line 1)

Next, create multiple if statements as required by the question (Line 3-13). The operator "<" denotes "smaller" and therefore carYear < 1967 means any year before 1967. On another hand, the operator ">" denotes "bigger" and therefore carYear > 1970 means any year after 1970.

The print statement in each of the if statements is done using the Python built-in function print(). The "\n" is an escape sequence that create a new line at the end of each printed phrase.

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