The fiducial points of the Celsius<span> and the </span>Fahrenheit<span> temperature </span>scales<span> are the boiling and freezing </span>points<span> of pure water at 1 atm of pressure.
In short, Your Answer would be Option D
Hope this helps!</span>
Friction is causing the skateboard to stop rolling.
The resistance of a wire is directly proportional to the length of the wire. That is the longer the length of the wire, the higher the resistance and the shorter the length of the wire, the smaller the resistance.
Answer:
2.96 × 10^4 N
Explanation:
1 atm = 101325 N/m², pressure inside the airtight room = 1.02 atm, pressure outside due to hurricane = 0.91 atm
net pressure directed outward = P inside - P outside
net pressure = 1.02 - 0.91 = 0.11 atm
where 1 atm = 101325N/m²
0.11 atm = 0.11 × 101325 N/m² = 11145.75 N/m²
area of the square wall = l × l where l is the length of the wall in meters = 1.63 × 1.63 = 2.6569
net pressure = net force / area
make net force subject of the formula
net force = net pressure × area = 11145.75 × 2.6569 = 2.96 × 10 ^4 N
Answer:
The mass rate of the cooling water required is: ![1'072988.5\frac{kg}{h}](https://tex.z-dn.net/?f=1%27072988.5%5Cfrac%7Bkg%7D%7Bh%7D)
Explanation:
First, write the energy balance for the condensator: The energy that enters to the equipment is the same that goes out from it; consider that there is no heat transfer to the surroundings and kinetic and potential energy changes are despreciable.
![{m_{w}}*{h_{w}}^{in}+m_s{h_{s}}^{in}=m_w{h_{w}}^{out}+m_s{h_{s}}^{out}](https://tex.z-dn.net/?f=%7Bm_%7Bw%7D%7D%2A%7Bh_%7Bw%7D%7D%5E%7Bin%7D%2Bm_s%7Bh_%7Bs%7D%7D%5E%7Bin%7D%3Dm_w%7Bh_%7Bw%7D%7D%5E%7Bout%7D%2Bm_s%7Bh_%7Bs%7D%7D%5E%7Bout%7D)
Where w refers to the cooling water and s to the steam flow. Reorganizing,
![m_w({h_{w}}^{out}-{h_{w}}^{in})=m_s({h_{s}}^{in}-{h_{s}}^{out})\\m_w=\frac{m_s({h_{s}}^{in}-{h_{s}}^{out})}{({h_{w}}^{out}-{h_{w}}^{in})}](https://tex.z-dn.net/?f=m_w%28%7Bh_%7Bw%7D%7D%5E%7Bout%7D-%7Bh_%7Bw%7D%7D%5E%7Bin%7D%29%3Dm_s%28%7Bh_%7Bs%7D%7D%5E%7Bin%7D-%7Bh_%7Bs%7D%7D%5E%7Bout%7D%29%5C%5Cm_w%3D%5Cfrac%7Bm_s%28%7Bh_%7Bs%7D%7D%5E%7Bin%7D-%7Bh_%7Bs%7D%7D%5E%7Bout%7D%29%7D%7B%28%7Bh_%7Bw%7D%7D%5E%7Bout%7D-%7Bh_%7Bw%7D%7D%5E%7Bin%7D%29%7D)
Write the difference of enthalpy for water as Cp (Tout-Tin):
![m_w=\frac{m_s({h_{s}}^{in}-{h_{s}}^{out})}{C_{pw}({T_{w}}^{out}-{T_{w}}^{in})}](https://tex.z-dn.net/?f=m_w%3D%5Cfrac%7Bm_s%28%7Bh_%7Bs%7D%7D%5E%7Bin%7D-%7Bh_%7Bs%7D%7D%5E%7Bout%7D%29%7D%7BC_%7Bpw%7D%28%7BT_%7Bw%7D%7D%5E%7Bout%7D-%7BT_%7Bw%7D%7D%5E%7Bin%7D%29%7D)
This equation will let us to calculate the mass rate required. Now, let's get the enthalpy and Cp data. The enthalpies can be read from the steam tables (I attach the tables I used). According to that,
and
can be calculated as:
.
The Cp of water at 25ºC (which is the expected average temperature for water) is: 4.176
. If the average temperature is actually different, it won't mean a considerable mistake. Also we know that
, so let's work with the limit case, which is
to calculate the minimum cooling water mass rate required (A higher one will give a lower temperature difference as a result). Finally, replace data:
![m_w=\frac{20000\frac{kg}{h}(2491.8-251.40)\frac{kJ}{kg} }{4.176\frac{kJ}{kgK} (10C)}=1'072988.5\frac{kg}{h}](https://tex.z-dn.net/?f=m_w%3D%5Cfrac%7B20000%5Cfrac%7Bkg%7D%7Bh%7D%282491.8-251.40%29%5Cfrac%7BkJ%7D%7Bkg%7D%20%7D%7B4.176%5Cfrac%7BkJ%7D%7BkgK%7D%20%2810C%29%7D%3D1%27072988.5%5Cfrac%7Bkg%7D%7Bh%7D)