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Naddika [18.5K]
2 years ago
10

The membrane that surrounds a certain type of living cell has a surface area of 4.7 x 10-9 m2 and a thickness of 1.3 x 10-8 m. A

ssume that the membrane behaves like a parallel plate capacitor and has a dielectric constant of 4.7. (a) The potential on the outer surface of the membrane is 79.5 mV greater than that on the inside surface. How much charge resides on the outer surface
Physics
1 answer:
vagabundo [1.1K]2 years ago
6 0

Answer:

Q = 1.2*10⁻¹² C

Explanation:

  • For any capacitor, by definition the capacitance C is equal to the relationship between the charge on one of the conductors and the potential difference between them, as follows:

       C = \frac{Q}{V}  (1)

  • For the special case of a parallel plate capacitor, just by application of Gauss' law to a rectangular surface half out of the outer surface, and half inside it, it can be showed that the value of the capacitance C is a parameter defined only by geometric constants, as follows:

       C = \frac{\epsilon_{0}*\epsilon _{r} * A}{d}  (2)

  • So, due to the left sides in (1) and (2) are equal each other, right sides must be equal too.
  • Replacing ε₀, εr (dielectric constant), A, d and V by their values, we can solve for Q, as follows:

       Q =\frac{\epsilon_{0} * \epsilon_{r} *A* V}{d} = \frac{(8.85*(4.7)^{2}*79.5)e-24 (F/m*m2*V)}{1.3e-8m} =  1.2e-12 C = 1.2 pC  (3)

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Answer:

The wavelength will be 4 cm, frequency will be 4.66 Hz and wave speed is 18.6 cm/sec

Explanation:

Given:

No. of crest = 13

No. of trough = 15

Time = 3 seconds

Hence, 1 crest or 1 trough = \frac{1}{2}\lambda

therefore,

13 C + 15 T = 28(\frac{1}{2}\lambda)

=14\lambda

Time given 3 seconds

  = \frac{3}{14}s

\nu= \frac{14}{3}

\nu= 4.6 Hz \approx 5 Hz

2 cm distance is travelled is time period

\lambda = 4 cm

Again wave will travel in 1 T = 4 cm

wave speed v =\lambda\times\nu

= 4\times\frac{14}{3}

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3 years ago
Explain why a roller coaster’s second hill cannot be taller than the first hill.
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There will not be enough momentum from the first hill to cross another hill if he same or larger size because of the way potential energy and kinetic energy works it will not be able go as high as it could go on he fist hill.
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3 years ago
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A man, a distance d=3~\text{m}d=3 m from a target, throws a ball at an angle \theta= 70^\circθ=70 ​∘ ​​ above the horizontal. If
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Answer:

The ball doesn't strike the building because it strikes the ground at d=1.62 meters.

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V= 5 m/s < 70º

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What exerts a centripetal force on a person running around a curve?
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Answer:

The inertial force of the body

Explanation:

Everybody that is moving in a curved path has an inertial force called centrifugal force.

The counterforce of the centrifugal force is called the centripetal force. It also acts on every rotating body.

This force is always directed towards the center of the origin of the curve.

The velocity of the object changes its direction and magnitude at any instant of time. But the speed and angular velocity of the object remains the same for uniform circular motion.

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3 years ago
The normal force acting on an object and the force of static friction do zero work on the object. However the reason that the wo
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Answer:

<em>The normal force is perpendicular to the displacement</em>

<em>The static friction force produces no displacement</em>

Explanation:

Work Done By Special Forces

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W=\vec F\ \vec r

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If the angle is zero, the work is at maximum, it the angle is 90°, the work is zero. If the angle is between 90° and 180°, the work is negative.

The normal force acts in the vertical direction when the object is being pushed horizontally. It means the angle between the force and the displacement is 90°, thus the work is

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Since in this case, there is no displacement, d=0, and the work is

W=F_r(0)cos180^o=0

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3 years ago
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