Why do organisms need nitrogen

Explain how we measure temperatures in our daily lives.

AnnyKZ [126]

Many devices have been invented to accurately measure temperature. It all started with the establishment of a temperature scale. This scale transformed the measurement of temperature into meaningful numbers.

In the early years of the eighteenth century, Gabriel Fahrenheit (1686-1736) created the Fahrenheit scale. He set the freezing point of water at 32 degrees and the boiling point at 212 degrees. These two points formed the anchors for his scale.

Later in that century, around 1743, Anders Celsius (1701-1744) invented the Celsius scale. Using the same anchor points, he determined the freezing temperature for water to be 0 degree and the boiling temperature 100 degrees. The Celsius scale is known as a Universal System Unit. It is used throughout science and in most countries.

There is a limit to how cold something can be. The Kelvin scale is designed to go to zero at this minimum temperature. The relationships between the different temperature scales are:

oK = 273.15 + oC oC = (5/9)*(oF-32) oF = (9/5)*oC+32

oF oC oK

Water boils 212 100 373

Room Temperature 72 23 296

Water Freezes 32 0 273

Absolute Zero -460 -273 0

At a temperature of Absolute Zero there is no motion and no heat. Absolute zero is where all atomic and molecular motion stops and is the lowest temperature possible. Absolute Zero occurs at 0 degrees Kelvin or -273.15 degrees Celsius or at -460 degrees Fahrenheit. All objects emit thermal energy or heat unless they have a temperature of absolute zero.

If we want to understand what temperature means on the molecular level, we should remember that temperature is the average energy of the molecules that composes a substance. The atoms and molecules in a substance do not always travel at the same speed. This means that there is a range of energy (the energy of motion) among the molecules. In a gas, for example, the molecules are traveling in random directions at a variety of speeds - some are fast and some are slow. Sometimes these molecules collide with each other. When this happens the higher speed molecule transfers some of its energy to the slower molecule causing the slower molecule to speed up and the faster molecule to slow down. If more energy is put into the system, the average speed of the molecules will increase and more thermal energy or heat will be produced. So, higher temperatures mean a substance has higher average molecular motion. We do not feel or detect a bunch of different temperatures for each molecule which has a different speed. What we measure as the temperature is always related to the average speed of the molecules in a system

3 0

3 years ago

Two loudspeakers are placed on a wall 2 m apart. A listener stands directly in front of one of the speakers, 81.7 m from the wal

OverLord2011 [107]

Answer:

The phase difference is $\Delta \phi = 1.9995 rad$

Explanation:

From the question we are told that

The distance between the loudspeakers is $d = 2m$

The distance of the listener from the wall $D = 81.7 \ m$

The frequency of the loudspeakers is $f = 4450Hz$

The velocity of sound is $v_s = 343 m/s$

The path difference of the sound wave that is getting to the listener is mathematically represented as

$\Delta z =\sqrt{d^2 + D^2} -D$

Substituting values

$\Delta z =\sqrt{2^2 + 81.7^2 } -81.7$

$\Delta z =0.0245m$

The phase difference is mathematically represented as

$\Delta \phi$ = $\frac{2 \pi}{\lambda } * \Delta z$

Where $\lambda$ is the wavelength which is mathematically represented as

$\lambda = \frac{v_s }{f}$

substituting value

$\lambda = \frac{343 }{4450}$

$\lambda = 0.0770 m$

Substituting value into the equation for phase difference

$\Delta \phi$ = $\frac{2 * 3.142 * 0.0245}{0.0770}$

$\Delta \phi = 1.9995 rad$

8 0

3 years ago

Communications satellites are placed in a circular orbit where they stay directly over a fixed point on the equator as the earth

zalisa [80]

Refer to the diagram shown below.

Given:
R = 6.37 x 10⁶ m, the radius of the earth
h = 3.58 x 10⁷ m, the height of the satellite above the earth's surface.
Therefore
R + h = 4.217 x 10⁷ m

In geosynchronous orbit, the period of rotation is 1 day.
Therefore the period is
T = (24 h)*(60 min/h)*(60 s/min) = 86400 s

The angular velocity is
ω = (2π rad)/(86400 s) = 7.2722 x 10⁻⁵ rad/s

Part (a)
The tangential speed is
v = (R+h)*ω
= (4.217 x 10⁷ m)*(7.2722 x 10⁻⁵ rad/s)
= 3066.7 m/s
= 3.067 km/s

Part (b)
The centripetal acceleration is
a = v²/(R+h)
= (3066.7 m/s)²/(4.217 x 10⁷ m)
= 0.223 m/s²

Answers:
(a) The speed is 3.067 km/s
(b) The acceleration is 0.223 m/s²