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Ganezh [65]
3 years ago
5

How is the frictional force produced?​

Physics
1 answer:
andrew-mc [135]3 years ago
5 0

Answer:

frictonal force due to the surface of irregularities

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An expensive vacuum system can achieve a pressure as low as 1.00×10^{-7} N/m^2 at 20ºC . How many atoms are there in a cubic cen
marta [7]

Answer:

24.70818432141\times 10^7\ atoms

Explanation:

P = Pressure = 1\times 10^{-7}\ N/m^2

V = Volume = 1 cm³

n = Amount of substance

N = Number of atoms

N_A = Avogadro's constant = 6.022\times 10^{23}\ /mol

R = Gas constant = 8.314 J/k mol

T = Temperature = 273.15+20 = 293.15 K

From the ideal gas law

PV=nRT\\\Rightarrow n=\frac{PV}{RT}

n=\frac{N}{N_A}

\frac{N}{N_A}=\frac{PV}{RT}\\\Rightarrow N=N_A\times \frac{PV}{RT}\\\Rightarrow N=\frac{1\times 10^{-7}\times 1\times 10^{-6}}{8.314\times 293.15}\times 6.022\times 10^{23}\\\Rightarrow N=24708184.32141\ atoms=24.70818432141\times 10^7\ atoms

The number of atoms is 24.70818432141\times 10^7\ atoms

8 0
3 years ago
Waves that move the particles of the medium parallel to the direction in which the waves are traveling are called
Nikolay [14]

1. a. longitudinal waves.

There are two types of waves:

- Transverse waves: in transverse waves, the oscillations of the wave occur in a direction perpendicular to the direction of propagation of the wave

- Longitudinal waves: in longitudinal waves, the oscillations of the waves occur parallel to the direction in which the waves are travelling.

So, these types of waves are called longitudinal waves.


2. d. a medium

There are two types of waves:

- Electromagnetic waves: these waves are produced by the oscillations of electric and magnetic field, and they can travel both in a medium and also in a vacuum (they do not need a medium to propagate)

- Mechanical waves: these waves are produced by the oscillations of the particles in a medium, so they need a medium to propagate - therefore, the correct choice is d. a medium


3. a. AM/FM radio

Analogue signals consist of continuous signals, which vary in a continuous range of values. On the contrary, digital signals consist of discrete signals, which can assume only some discrete values. For AM and FM radios, signals are transmitted by using analogue signals.

5 0
3 years ago
A ball is tossed straight up from the surface of a small, spherical asteroid with no atmosphere. The ball rises to a height equa
alukav5142 [94]

Answer:

d. equal to one-fourth the acceleration at the surface of the asteroid.

Explanation:

The explanation is attached as a picture with this answer

Newton's law of universal gravitation is being used to compare the accelerations at the surface and at the top of the ball's path.

as it can be seen in the explanation that the proportional form of the equation is used because we do not need to necessarily use to final form with "G" for comparison calculations.

As per the given scenario only difference between the two points in the gravitational field is the distance from center of the spherical asteroid, i.e. r.

It is  taken 2r for the top is the path. hence we obtain (1/4)g as our answer.

4 0
3 years ago
Read 2 more answers
When light is directed on a metal surface, the kinetic energies of the photoelectrons a) are random b) vary with the frequency o
jekas [21]

Answer:

b) vary with the frequency of the light

Explanation:

The phone electric effect can be expressed as

K.E=(hv -W•)

Where K.E is the Kinectic energy

W• = work function of the metal

ν =frequency of the radiation

h = Planck's constat

Then, we can see that K.E is proportional linearly to "v" in the equation above.

Therefore, When light is directed on a metal surface, the kinetic energies of the photoelectrons vary with the frequency of the light

5 0
2 years ago
In the lesson a thermos is presented as an example of an isolated energy system. How could you change the thermos into an open e
iVinArrow [24]
If you want to change the thermos into an open energy system, you have to remove the lid. Once the lid is removed, the energy is no longer contained inside the thermos bottle. From the bottle, the energy dissipates to the environment.
7 0
3 years ago
Read 2 more answers
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