The whole definition of frequency is: <em>How often something happens. </em>
Especially referring to something that happens over and over and over and over.
One example is Choice-C: How often the particles of a medium vibrate.
"Frequency" comes from the word "frequent". That means "often", and "frequency" just means "often-ness" ... HOW often the thing happens.
Some other examples:
Frequency of jump-roping . . . maybe 60 per minute .
Frequency of rain . . . maybe 5 per month .
Frequency of an AM radio station . . . maybe 1 million waves per second.
(If it's something <u><em>per second</em></u>, then we call it "Hertz". That's not for the car rental company. It's for Heinrich Hertz, the German Physicist who was the first one to prove that electromagnetic waves exist. He sent radio waves all the way ACROSS HIS LABORATORY and detected them at the other side ( ! ), in 1887.)
Frequency of the wiggles in the sound wave coming out of a trumpet playing the note ' A ' . . . 440 Hertz.
Frequency of sunrise and the Chicago Tribune newspaper . . . 1 per day
Frequency of the cycle of Moon phases and an average human woman's ovulation cycle: 1 per 29.531 days, 1 per ~28 days .
Explanation:
Since, entropy is the measure of degree of randomness. So, more randomly the molecules of a substance are moving more will be its entropy.
- For example, when a solid melts then it means heat is absorbed by it due to which its molecules have gained energy. As a result, they collide with each other and hence, entropy will increase.
- Evaporation of a liquid will also cause the liquid to change its state from liquid to gas. This means molecules will go far away from each other leading to an increase in the entropy.
- Sublimation is a process of conversion of a solid into gaseous phase without going through liquid phase. So, in this case also entropy will increase due to gain in energy by the molecules of a solid.
- In freezing, molecules of a substance come closer to each other and acquire less energy. Hence, entropy decreases.
- Mixing is a process of combining two or more substances physically with each other. This leads to increase in entropy of a substance.
- In separation molecules are separated from each other leading to a decrease in energy. Hence, entropy will also decrease.
- Diffusion is a process in which molecules are able to rapidly move from one place to another. Hence, entropy increases when diffusion takes place.
Thus, we can conclude that melting of a solid, evaporation of a liquid, sublimation, mixing and diffusion involve an increase in the entropy of the system under consideration.
Answer:
Explanation:
The rate of change in volume is proportional to the surface area:
dV/dt = kA
Integrating:
V = kAt + C
At t=0, V = s, so:
s = kA(0) + C
C = s
Therefore:
V = kAt + s
Answer:
Explanation:
Let the potential difference between the plate is V . Then in the first case
Electric field E between plate
E₁ = V / d
where d is separation between plate
When the plate separation becomes d / 2
Electric field E between plate
E₂ = V / d /2
= 2 V / d =2E₁
Or twice the earlier field
<u>Answer:</u>
Yes
<u>Explanation:</u>
Average velocity is the ratio of total displacement and time taken for that displacement:
This means if displacement is zero, then average velocity will also be zero.
Displacement is zero when an object moves some distance in one direction, and then moves the same distance but in the opposite direction.
∴ As it is possible for displacement to be zero, it is also possible for average velocity to be zero.
