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Ludmilka [50]
3 years ago
12

Which sentence about the technology design process is true

Engineering
1 answer:
Aleks [24]3 years ago
5 0
The answer is the second one b
You might be interested in
A reversible refrigeration cycle operates between cold and hot reservoirs at temperatures TC and TH, respectively. (a) If the co
podryga [215]

Answer:

a) T_{H} = 1.967\,^{\circ}F, b) COP_{R} = 9.105, c) T_{H} = 115.934\,^{\circ}F, d) COP_{R} = 6.995, e) T_{H} = 25.129\,^{\circ}C

Explanation:

a) The coefficient of performance of the reversible refrigeration cycle is:

COP_{R} = \frac{T_{C}}{T_{H}-T_{C}}

10 = \frac{419.67\,R}{T_{H}-419.67\,R}

The temperature of the hot reservoir is:

10\cdot T_{H} - 4196.7 = 419.67

T_{H} = 461.637\,R

T_{H} = 1.967\,^{\circ}F

b) The coefficient of performance is:

COP_{R} = \frac{273.15\,K}{303.15\,K-273.15\,K}

COP_{R} = 9.105

c) The temperature of the hot reservoir can be determined with the help of the following relation:

\frac{Q_{C}}{Q_{H}-Q_{C}} = \frac{T_{C}}{T_{H}-T_{C}}

\frac{500\,BTU}{600\,BTU-500\,BTU} = \frac{479.67\,R}{T_{H}-479.67\,R}

5 = \frac{479.67\,R}{T_{H}-479.67\,R}

5\cdot T_{H} - 2398.35 = 479.67

T_{H} = 575.604\,R

T_{H} = 115.934\,^{\circ}F

d) The coefficient of performance is:

COP_{R} = \frac{489.67\,R}{559.67\,R-489.67\,R}

COP_{R} = 6.995

e) The temperature of the cold reservoir is:

8.9 = \frac{268.15\,K}{T_{H}-268.15\,K}

8.9\cdot T_{H} - 2386.535 = 268.15

T_{H} = 298.279\,K

T_{H} = 25.129\,^{\circ}C

8 0
3 years ago
A commuter train traveling at 50 mi/h is 3 mi from a station. The train then decelerates so that its speed is 15 mi/h when it is
jonny [76]

Answer:

a) t = 277.477\,s\,(4.625\min), b) v_{f} = 0\,\frac{mi}{h}, c) a = -0.128\,\frac{ft}{s^{2}}

Explanation:

a) The deceleration experimented by the commuter train in the first 2.5 miles is:

a=\frac{[(15\,\frac{mi}{h} )\cdot (\frac{5280\,ft}{1\,mi} )\cdot (\frac{1\,h}{3600\,s} )]^{2}-[(50\,\frac{mi}{h} )\cdot (\frac{5280\,ft}{1\,mi} )\cdot (\frac{1\,h}{3600\,s} )]^{2}}{2\cdot (2.5\,mi)\cdot (\frac{5280\,ft}{1\,mi} )}

a = -0.185\,\frac{ft}{s^{2}}

The time required to travel is:

t = \frac{(15\,\frac{mi}{h} )\cdot (\frac{5280\,ft}{1\,fi} )\cdot(\frac{1\,h}{3600\,s} )-(50\,\frac{mi}{h} )\cdot (\frac{5280\,ft}{1\,fi} )\cdot(\frac{1\,h}{3600\,s} )}{-0.185\,\frac{ft}{s^{2}} }

t = 277.477\,s\,(4.625\min)

b) The commuter train must stop when it reaches the station to receive passengers. Hence, speed of train must be v_{f} = 0\,\frac{mi}{h}.

c) The final constant deceleration is:

a = \frac{(0\,\frac{mi}{h} )\cdot (\frac{5280\,ft}{1\,mi} )\cdot(\frac{1\,h}{3600\,s} )-(15\,\frac{mi}{h} )\cdot (\frac{5280\,ft}{1\,mi} )\cdot(\frac{1\,h}{3600\,s} )}{(2.875\,min)\cdot (\frac{60\,s}{1\,min} )}

a = -0.128\,\frac{ft}{s^{2}}

7 0
3 years ago
What is the activation energy (Q) for a vacancy formation if 10 moles of a metal have 2.3 X 10^13 vacancies at 425°C?
Yakvenalex [24]

Answer:

Activation\ Energy=2.5\times 10^{-19}\ J

Explanation:

Using the expression shown below as:

N_v=N\times e^{-\frac {Q_v}{k\times T}

Where,

N_v is the number of vacancies

N is the number of defective sites

k is Boltzmann's constant = 1.38\times 10^{-23}\ J/K

{Q_v} is the activation energy

T is the temperature

Given that:

N_v=2.3\times 10^{13}

N = 10 moles

1 mole = 6.023\times 10^{23}

So,

N = 10\times 6.023\times 10^{23}=6.023\times 10^{24}

Temperature = 425°C

The conversion of T( °C) to T(K) is shown below:

T(K) = T( °C) + 273.15  

So,  

T = (425 + 273.15) K = 698.15 K  

T = 698.15 K

Applying the values as:

2.3\times 10^{13}=6.023\times 10^{24}\times e^{-\frac {Q_v}{1.38\times 10^{-23}\times 698.15}

ln[\frac {2.3}{6.023}\times 10^{-11}]=-\frac {Q_v}{1.38\times 10^{-23}\times 698.15}

Q_v=2.5\times 10^{-19}\ J

4 0
3 years ago
What might cause a shotgun to explode?
Tanzania [10]

Answer:

When you pull the trigger to shoot a shotshell from a shotgun or a cartridge from a rifle or handgun, the firing pin strikes the primer in the base of the cartridge or shotshell. This causes the primer to explode. The spark from the primer ignites the gunpowder, which burns rapidly and converts to a gas.

Explanation:

3 0
3 years ago
Read 2 more answers
A circular hoop sits in a stream of water, oriented perpendicular to the current. If the area of the hoop is doubled, the flux (
natka813 [3]

Answer:

The flux (volume of water per unit time) through the hoop will also double.

Explanation:

The flux = volume of water per unit time = flow rate of water through the hoop.

The Flow rate of water through the hoop is proportional to the area of the hoop, and the velocity of the water through the hoop.

This means that

Flow rate = AV

where A is the area of the hoop

V is the velocity of the water through the hoop

This flow rate = volume of water per unit time = Δv/Δt =Q

From all the above statements, we can say

Q = AV

From the equation, if we double the area, and the velocity of the stream of water through the hoop does not change, then, the volume of water per unit time will also double or we can say increases by a factor of 2

3 0
3 years ago
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