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3 years ago

What is the main role of the cell membrane?

2 answers:

8 0

The plasma membrane, or the cell membrane, provides protection for a cell. It also provides a fixed environment inside the cell, and that membrane has several different functions.

densk [106]3 years ago

6 0

Answer:

The plasma membrane, or the cell membrane, provides protection for a cell. It also provides a fixed environment inside the cell, and that membrane has several different functions. One is to transport nutrients into the cell and also to transport toxic substances out of the cell.

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Please can someone give a clear explanantion, <br><br> no extra links thanks

Tems11 [23]

Answer:

the extension recorded by the student would be smaller than the actual extension of the spring

3 0

3 years ago

In a Hydrogen atom an electron rotates around a stationary proton in a circular orbit with an approximate radius of r =0.053nm.

leonid [27]

Answer:

(a): $F_e = 8.202\times 10^{-8}\ \rm N.$

(b): $F_g = 3.6125\times 10^{-47}\ \rm N.$

(c): $\dfrac{F_e}{F_g}=2.27\times 10^{39}.$

Explanation:

Given that an electron revolves around the hydrogen atom in a circular orbit of radius r = 0.053 nm = 0.053 $\times 10^{-9}$ m.

Part (a):

According to Coulomb's law, the magnitude of the electrostatic force of interaction between two charged particles of charges $q_1$ and $q_2$ respectively is given by

$F_e = \dfrac{k|q_1||q_2|}{r^2}$

where,

$k$ = Coulomb's constant = $9\times 10^9\ \rm Nm^2/C^2.$
$r$ = distance of separation between the charges.

For the given system,

The Hydrogen atom consists of a single proton, therefore, the charge on the Hydrogen atom, $q_1 = +1.6\times 10^{-19}\ C.$

The charge on the electron, $q_2 = -1.6\times 10^{-19}\ C.$

These two are separated by the distance, $r = 0.053\times 10^{-9}\ m.$

Thus, the magnitude of the electrostatic force of attraction between the electron and the proton is given by

$F_e = \dfrac{(9\times 10^9)\times |+1.6\times 10^{-19}|\times |-1.6\times 10^{-19}|}{(0.053\times 10^{-9})^2}=8.202\times 10^{-8}\ \rm N.$

Part (b):

The gravitational force of attraction between two objects of masses $m_1$ and $m_1$ respectively is given by

$F_g = \dfrac{Gm_1m_2}{r^2}.$

where,

$G$ = Universal Gravitational constant = $6.67\times 10^{-11}\ \rm Nm^2/kg^2.$
$r$ = distance of separation between the masses.

For the given system,

The mass of proton, $m_1 = 1.67\times 10^{-27}\ kg.$

The mass of the electron, $m_2 = 9.11\times 10^{-31}\ kg.$

Distance between the two, $r = 0.053\times 10^{-9}\ m.$

Thus, the magnitude of the gravitational force of attraction between the electron and the proton is given by

$F_g = \dfrac{(6.67\times 10^{-11})\times (1.67\times 10^{-27})\times (9.11\times 10^{-31})}{(0.053\times 10^{-9})^2}=3.6125\times 10^{-47}\ \rm N.$

The ratio $\dfrac{F_e}{F_g}$ :

$\dfrac{F_e}{F_g}=\dfrac{8.202\times 10^{-8}}{3.6125\times 10^{-47}}=2.27\times 10^{39}.$

6 0

3 years ago

The de Broglie wave is produced only by sub atomic particle and photon. O True O False

Alina [70]

Answer:

True

Explanation:

Matter can be in the form of a particle or a wave. This is known as the dual nature of matter. This concept was proposed by Louis de Broglie and was named after him. This phenomenon has been observed for all the elementary particles.

The de Broglie wavelength is given by

$\lambda=\frac{h}{p}=\frac{h}{mv}$

Where

h = Planck's constant

p = Particles momentum

m = Mass of particle

v = Velocity of particle

8 0

3 years ago

Two objects separated by a distance r are each carrying a charge q The magnitude of the force exerted on the second object by th

Sindrei [870]

Answer:F=4F

Explanation: Columbs law states that The force between the two point charges is directly proportional to the product of charges and inversely proportional to the square of distance between them

Force between the two charges is given by

F=K*q1*q2/r^2

if one charge become 4 times, new force is,

F=4(K*q1*q2)/r^2

F=4F

Where q1 and q2 are the point charges

r is the distance between the two charges

K is a constant of proportion called electrostatic force

4 0

3 years ago

Which of the following changes would cause the fusion rate in the Sun’s core to increase? Check all that apply. View Available H

fredd [130]

Answer:

1. An increase in the core temperature

2. A decrease in the core radius.

Explanation:

The sun is a Main Sequence star. A Main Sequence star is powered by fusing hydrogen into Helium within its core.

For this fusion to take place, a temperature of at least 10 million Kelvin is required, beyond this point, the fusion rate is directly related to the core temperature. If the temperature increases, the fusion rate will greatly increase.

Something similar happens if the core reduces its radius. This can happen at the end of the star's lifetime, shortly before it becomes a red giant. Once the hydrogen is depleted, the core will start to shrink because the force of gravity, and as it gets smaller, gets more compressed, and its temperature increases. The outer layers of remaining Hydrogen that were outside the core now begin to heat up, and as the core continues to shrink, the star gets hot enough to begin the fusion process again, and the fusion rate can even be higher than it was during the first phase of the star, as the star becomes a Red Giant.

7 0

3 years ago