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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:
a)
b)
Explanation:
Given:
Frequency of the whistle, f = 564 Hz
Radius of the circle, r = 71.2 cm = 0.712 m
Angular speed, ω = 17.1 rad/s
speed of source, = rω = 0.712 × 17.1 = 12.1752 m/s
speed of sound, v = 343 m/s
Now, applying the Doppler's effect formula, we have
where,
= relative speed of the detector with respect to medium = 0
a) for lowest frequency, we have the formula as:
on substituting the values, we get
or
b) for maximum frequency, we have the formula as:
on substituting the values, we get
or