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Inessa [10]
3 years ago
9

A water pump delivers 6 hp of shaft power when operating. The pressure differential between the outlet and the inlet of the pump

is measured to be 1.2 psi when the flow rate is 10 ft3/s, and the velocity changes to 5 ft/s from 2 ft/s as the water passes through the pump. Determine the mechanical efficiency of this pump assuming the water density to be 62.4 lbm/ft3 (written in decimal form with 3 significant figures).
Engineering
1 answer:
frez [133]3 years ago
5 0

Answer: Pump efficiency = 0.585 = 58.5%

Explanation: Pump efficiency = (power gained by the fluid)/(power supplied by the shaft)

Power gained by the fluid = Q(ΔP) + m(((v2)^2) - ((v1)^2))/2

Where Q = volumetric flow rate = 10 ft3/s = 0.283 m3/s

ΔP = 1.2 psia = 8273.709 Pa

m = mass flow rate = density × volumetric flow rate

Density = 62.4 lbm/ft3 = 999.52 kg/m3

m = 999.52 × 0.283 = 282.86 kg/s

v2 = 5ft/s = 1.524 m/s

v1 = 2ft/s = 0.61 m/s

Q(ΔP) = 0.283 × 8273.709 = 2341.46 W

Power from change in kinetic energy = m(((v2)^2) - ((v1)^2))/2 = 275.92 W

Power gained by the fluid = 2341.46 + 275.92 = 2617.38 W

Power supplied by shaft = 6hp = 6 × 746 = 4476 W

Efficiency = 2617.38/4476 = 0.58475 = 0.585 to 3s.f

QED!

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A pitfall cited in Section 1.10 is expecting to improve the overall performance of a computer by improving only one aspect of th
Oxana [17]

Answer:

a) For this case the new time to run the FP operation would be reduced 20% so that means 100-20% =80% from the original time

(1-0.2)*70 s =56s

The reduction on this case is 70-56 s=14s

And since the new total time would be given by 250-14=236 s

b) For this case the total time is reduced 20%  so that means that the new total time would be (1-0.2)=0.8 times the original total time (1-0.2) *250s =200 s

The original time for INT operations is calculated as:

250 = 70+85+40 +t_{INT}

t_{INT}=55s

For this part the only time that was changed is assumed the INT operations so then:

200 = 70+85+40 \Delta t_{INT}

And then: \Delta t_{INT}= 200-70-85-40=5 s

c) A reduction of the total time implies that the total time would be 205 s from the results above. And the time for FP is 70, for L/S is 85 and for INT operations is 55 s, so then if we add 70+85+55=210s, we see that 210>205 so then we cannot reduce the total time 20% just reducing the branch intructions.

Explanation:

From the info given we know that a computer running a program that requires 250 s, with 70 s spent executing FP instructions, 85 s executed L/S instructions and 40 s spent executing branch instructions.

Part 1

For this case the new time to run the FP operation would be reduced 20% so that means 100-20% =80% from the original time

(1-0.2)*70 s =56s

The reduction on this case is 70-56 s=14s

And since the new total time would be given by 250-14=236 s

Part 2

For this case the total time is reduced 20%  so that means that the new total time would be (1-0.2)=0.8 times the original total time (1-0.2) *250s =200 s

The original time for INT operations is calculated as:

250 = 70+85+40 +t_{INT}

t_{INT}=55s

For this part the only time that was changed is assumed the INT operations so then:

200 = 70+85+40 \Delta t_{INT}

And then: \Delta t_{INT}= 200-70-85-40=5 s

And we can quantify the decrease using the relative change:

\% Change = \frac{5s}{55 s} *100 = 9.09\% of reduction

Part 3

A reduction of the total time implies that the total time would be 205 s from the results above. And the time for FP is 70, for L/S is 85 and for INT operations is 55 s, so then if we add 70+85+55=210s, we see that 210>205 so then we cannot reduce the total time 20% just reducing the branch intructions.

8 0
3 years ago
As described in "A Note About Bacterial Reproduction -- and the "Culture Bias,"" the organism Epulopisciumdoes not divide by bin
zloy xaker [14]

Answer:

A

Explanation:

The best method that will yield significantly more accurate result is to use spectrophotometer to read the turbidity of the sample and increase in turbidity is associated with increase biomass.

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4.2 A vapor compression refrigeration machine uses 30kW of electric power to produce 50 tons of cooling. What is
stellarik [79]

Answer:

5.833

Explanation:

Coefficient of Perfomance (COP) is the ratio of refrigeration effect to power input.

COP=\frac {RE}{P} where RE is refrigeration effect and P is power input

Here, the power input is given as 30 kW

We also know that 1 ton cooling is equivalent to 3.5 kW hence for 50 tons, RE=50*3.5=175 kW

Now the COP=\frac {175}{30}=5.833

6 0
3 years ago
Select the level of education that is best demonstrated in each example.
Nastasia [14]

Answer:

masters

associate

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Explanation:

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Wewaii [24]

Answer:

hazardous chemicals leaving the workplace is labeled, tagged or marked with the following information: product identifier; signal word; hazard statement

Explanation:

this is so you know what chemicals are in it

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