Answer:
Impulse =14937.9 N
tangential force =14937.9 N
Explanation:
Given that
Mass of car m= 800 kg
initial velocity u=0
Final velocity v=390 km/hr
Final velocity v=108.3 m/s
So change in linear momentum P= m x v
P= 800 x 108.3
P=86640 kg.m/s
We know that impulse force F= P/t
So F= 86640/5.8 N
F=14937.9 N
Impulse force F= 14937.9 N
We know that
v=u + at
108.3 = 0 + a x 5.8
![a=18.66\ m/s^2](https://tex.z-dn.net/?f=a%3D18.66%5C%20m%2Fs%5E2)
So tangential force F= m x a
F=18.66 x 800
F=14937.9 N
Answer:
the heat transfer from the pipe will decrease when the insulation is taken off for r₂< ![r_{cr}](https://tex.z-dn.net/?f=r_%7Bcr%7D)
where;
r₂ = outer radius
= critical radius
Explanation:
Note that the critical radius of insulation depends on the thermal conductivity of the insulation k and the external convection heat transfer coefficient h .
![r_{cr} =\frac{k}{h}](https://tex.z-dn.net/?f=r_%7Bcr%7D%20%3D%5Cfrac%7Bk%7D%7Bh%7D)
The rate of heat transfer from the cylinder increases with the addition of insulation for outer radius less than critical radius (r₂<
) 0, and reaches a maximum when r₂ =
, and starts to decrease for r₂<
. Thus, insulating the pipe may actually increase the rate of heat transfer from the pipe instead of decreasing it when r₂<
.
Explanation:
Engineering is science in practical terms. It is the application of scientific findings in problem solving and creating a better world.
How does technological advancements create more problems for engineers?
- Loss of job to automation: the world is driving at automating work processes through the use of specially designed and crafted machinery. Work is now properly being done using machines with little to no human input in the whole process. This is a huge let off for engineers. Engineers have to compete with machines which are their own inventions for jobs now.
- Fast paced work environment: machines can handle work more efficiently and faster than the people making them. There is an increasing race between engineers and their own inventions today for better product delivery. Unless a machine is faulty, they are more productive and efficient than man. This can cause engineers to want to catch up with their own inventions leading to a work life of stress.
- Environmental problems they cannot solve: most inventions use components from the environment. They release effluents that are very difficult to be properly disposed or stored. This is a huge problem for engineers and can lead to ethical calls from the government and the populace. In short, they can create problems they are expected to solve but cannot solve.
- Social problems: engineers can be portrayed as terrible beings for their own inventions. This leads to psychological problems on a good and creative invention. For example, rare earth metals in DR Congo are instrumental in making solar panels, but mining of these metals have forced several thousands of people into hard and intense labor on mines; there is a call on technological firms to stop exploiting people this way for their own gains.
- Misuse of technology: any good technology can be put into the wrong use. A nuclear reaction can be packaged into a bomb and also, it can be the center of electricity generation on a commercial scale. How can engineers solve this kind of problem? Technological inventions are subjective in their usage.
Learn more:
New technology brainly.com/question/5768621
#learnwithBrainly
Explanation:
The obtained data from water properties tables are:
Point 1 (condenser exit) @ 8 KPa, saturated fluid
![h_{f} = 173.358 \\h_{fg} = 2402.522](https://tex.z-dn.net/?f=h_%7Bf%7D%20%3D%20173.358%20%5C%5Ch_%7Bfg%7D%20%3D%202402.522)
Point 2 (Pump exit) @ 18 MPa, saturated fluid & @ 4 MPa, saturated fluid
![h_{2a} = 489.752\\h_{2b} = 313.2](https://tex.z-dn.net/?f=h_%7B2a%7D%20%3D%20%20489.752%5C%5Ch_%7B2b%7D%20%3D%20%20313.2)
Point 3 (Boiler exit) @ 18 MPa, saturated steam & @ 4 MPa, saturated steam
![h_{3a} = 2701.26 \\s_{3a} = 7.1656\\h_{3b} = 2634.14\\s_{3b} = 7.6876](https://tex.z-dn.net/?f=h_%7B3a%7D%20%3D%202701.26%20%5C%5Cs_%7B3a%7D%20%3D%207.1656%5C%5Ch_%7B3b%7D%20%3D%202634.14%5C%5Cs_%7B3b%7D%20%3D%207.6876)
Point 4 (Turbine exit) @ 8 KPa, mixed fluid
![x_{a} = 0.8608\\h_{4a} = 2241.448938\\x_{b} = 0.9291\\h_{4b} = 2405.54119](https://tex.z-dn.net/?f=x_%7Ba%7D%20%3D%200.8608%5C%5Ch_%7B4a%7D%20%3D%202241.448938%5C%5Cx_%7Bb%7D%20%3D%200.9291%5C%5Ch_%7B4b%7D%20%3D%202405.54119)
Calculate mass flow rates
Part a) @ 18 MPa
mass flow
![\frac{100*10^6 }{w_{T} - w_{P}} = \frac{100*10^3 }{(h_{3a} - h_{4a}) - (h_{2a} - h_{f})}\\\\= \frac{100*10^ 3}{(2701.26 - 2241.448938 ) - (489.752 - 173.358)}\\\\= 697.2671076 \frac{kg}{s} = 2510161.587 \frac{kg}{hr}](https://tex.z-dn.net/?f=%5Cfrac%7B100%2A10%5E6%20%7D%7Bw_%7BT%7D%20-%20w_%7BP%7D%7D%20%3D%20%5Cfrac%7B100%2A10%5E3%20%7D%7B%28h_%7B3a%7D%20%20-%20h_%7B4a%7D%29%20-%20%28h_%7B2a%7D%20%20-%20h_%7Bf%7D%29%7D%5C%5C%5C%5C%3D%20%5Cfrac%7B100%2A10%5E%203%7D%7B%282701.26%20%20-%202241.448938%20%29%20-%20%28489.752%20%20-%20173.358%29%7D%5C%5C%5C%5C%3D%20697.2671076%20%5Cfrac%7Bkg%7D%7Bs%7D%20%3D%202510161.587%20%5Cfrac%7Bkg%7D%7Bhr%7D)
Heat transfer rate through boiler
![Q_{in} = mass flow * (h_{3a} - h_{2a})\\Q_{in} = (697.2671076)*(2701.26-489.752)\\\\Q_{in} = 1542011.787 W](https://tex.z-dn.net/?f=Q_%7Bin%7D%20%20%3D%20mass%20flow%20%2A%20%28h_%7B3a%7D%20-%20%20h_%7B2a%7D%29%5C%5CQ_%7Bin%7D%20%3D%20%28697.2671076%29%2A%282701.26-489.752%29%5C%5C%5C%5CQ_%7Bin%7D%20%3D%201542011.787%20W)
Heat transfer rate through condenser
![Q_{out} = mass flow * (h_{4a} - h_{f})\\Q_{out} = (697.2671076)*(2241.448938-173.358)\\\\Q_{out} = 1442011.787 W](https://tex.z-dn.net/?f=Q_%7Bout%7D%20%20%3D%20mass%20flow%20%2A%20%28h_%7B4a%7D%20-%20%20h_%7Bf%7D%29%5C%5CQ_%7Bout%7D%20%3D%20%28697.2671076%29%2A%282241.448938-173.358%29%5C%5C%5C%5CQ_%7Bout%7D%20%3D%201442011.787%20W)
Thermal Efficiency
![n = \frac{W_{net} }{Q_{in} } = \frac{100*10^3}{1542011.787} \\\\n = 0.06485](https://tex.z-dn.net/?f=n%20%3D%20%5Cfrac%7BW_%7Bnet%7D%20%20%7D%7BQ_%7Bin%7D%20%7D%20%3D%20%5Cfrac%7B100%2A10%5E3%7D%7B1542011.787%7D%20%20%5C%5C%5C%5Cn%20%3D%200.06485)
Part b) @ 4 MPa
mass flow
![\frac{100*10^6 }{w_{T} - w_{P}} = \frac{100*10^3 }{(h_{3b} - h_{4b}) - (h_{2b} - h_{f})}\\\\= \frac{100*10^ 3}{(2634.14 - 2405.54119 ) - (313.12 - 173.358)}\\\\= 1125 \frac{kg}{s} = 4052374.235 \frac{kg}{hr}](https://tex.z-dn.net/?f=%5Cfrac%7B100%2A10%5E6%20%7D%7Bw_%7BT%7D%20-%20w_%7BP%7D%7D%20%3D%20%5Cfrac%7B100%2A10%5E3%20%7D%7B%28h_%7B3b%7D%20%20-%20h_%7B4b%7D%29%20-%20%28h_%7B2b%7D%20%20-%20h_%7Bf%7D%29%7D%5C%5C%5C%5C%3D%20%5Cfrac%7B100%2A10%5E%203%7D%7B%282634.14%20%20-%202405.54119%20%29%20-%20%28313.12%20%20-%20173.358%29%7D%5C%5C%5C%5C%3D%201125%20%5Cfrac%7Bkg%7D%7Bs%7D%20%3D%204052374.235%20%5Cfrac%7Bkg%7D%7Bhr%7D)
Heat transfer rate through boiler
![Q_{in} = mass flow * (h_{3b} - h_{2b})\\Q_{in} = (1125.65951)*(2634.14-313.12)\\\\Q_{in} = 2612678.236 W](https://tex.z-dn.net/?f=Q_%7Bin%7D%20%20%3D%20mass%20flow%20%2A%20%28h_%7B3b%7D%20-%20%20h_%7B2b%7D%29%5C%5CQ_%7Bin%7D%20%3D%20%281125.65951%29%2A%282634.14-313.12%29%5C%5C%5C%5CQ_%7Bin%7D%20%3D%202612678.236%20W)
Heat transfer rate through condenser
![Q_{out} = mass flow * (h_{4b} - h_{f})\\Q_{out} = (1125)*(2405.54119-173.358)\\\\Q_{out} = 2511206.089 W](https://tex.z-dn.net/?f=Q_%7Bout%7D%20%20%3D%20mass%20flow%20%2A%20%28h_%7B4b%7D%20-%20%20h_%7Bf%7D%29%5C%5CQ_%7Bout%7D%20%3D%20%281125%29%2A%282405.54119-173.358%29%5C%5C%5C%5CQ_%7Bout%7D%20%3D%202511206.089%20W)
Thermal Efficiency
![n = \frac{W_{net} }{Q_{in} } = \frac{100*10^3}{1542011.787} \\\\n = 0.038275](https://tex.z-dn.net/?f=n%20%3D%20%5Cfrac%7BW_%7Bnet%7D%20%20%7D%7BQ_%7Bin%7D%20%7D%20%3D%20%5Cfrac%7B100%2A10%5E3%7D%7B1542011.787%7D%20%20%5C%5C%5C%5Cn%20%3D%200.038275)