At a given point on a horizontal streamline in flowing air, the static pressure is â2.0 psi (i.e., a vacuum) and the velocity is
1 answer:
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Answer:
12432 cal.
Explanation:
The process to change ice at -32 ºC to steam at 182 ºC can be divided into 5 steps:
1. Heat the ice to 0 ºC, which is the fusion temperature.
2. Melt the ice (obtaining liquid water), which is a process at constant pressure and temperature, so the liquid obtained is also at 0ºC.
3. Heat the liquid water from 0 ºC to 100 ºC, which is the vaporization normal temperature of the water.
4. Vaporization of all the water; this is also a process that occurs at constant pressure and temperature, so the produced steam will be at 100ºC.
5. Heat the steam from 100 ºC to 182 ºC.
Each process has a required energy, and the sum of the energy required for each and all of the steps is the total amount of energy required for the whole process:
is a heating process for the ice, so we know that the energy required is proportional to the temperature difference through the specific heat:
is a phase change process, so we do not use the specific heat (sensible heat), but the fusion heat (latent heat), so:
Analogously,
Finally, the total energy required is:
Answer:
1) c.
2) a.)
Explanation:
1)
- At any wave, if its waveform repeats itself every time interval T, it is said that the wave is periodic, with a period T, which is the time needed to complete an entire cycle. The other options refer at the way in the waves propagates (longitudinal or transversal) and to the type of waveform (sinusoidal), so the right answer is c).
2)
- At any wave that propagates at a constant speed, there exists a fixed relationship between the velocity v, the frequency f and the wavelength λ, as follows:
- So in order to v keep constant, if the frequency is increased, the wavelength will decrease in the same proportion, so a) is the right answer.