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3 years ago

Why do we charge a capacitor under a DC voltage source only?

2 answers:

8 0

Capacitors are essentially two plates that are mounted next to each other, with a gap between them so that the plates don't touch. Direct current can't jump the gap between plates, because it would take a massive amount of voltage to force the electron to jump the gap between plates. The electrons hit the plate and stop. Alternating current, on the other hand, is moving the electrons back and forth in place -- so the plate on one side of the capacitor is constantly having electrons pushed in and then pulled back out. This motion creates a small electric field which induces the same alternating current in the other plate, because electric fields can jump the gap between plates. Therefore it is possible with ac supply only to make capcitor work.

Anit [1.1K]3 years ago

7 0

Because there is always risk of death

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A 15.0 kg fish swimming at 1.10 m/s suddenly gobbles up a 4.50 kg fish that is initially stationary. Ignore any drag effects of

Nana76 [90]

Answer

given.

Mass of big fish = 15 Kg

speed of big fish = 1.10 m/s

mass of the small fish = 4.50 Kg

speed of the fish after eating small fish =?

a) using conservation of momentum

m₁v₁ + m₂v₂ = (m₁+m₂) V

15 x 1.10 + 4.50 x 0 = (15 + 4.5)V

16.5 = 19.5 V

V = 0.846 m/s

b) Kinetic energy before collision

$KE_1 = \dfrac{1}{2}m_1v_1^2 + \dfrac{1}{2}m_2v_2^2$

$KE_1 = \dfrac{1}{2}\times 15 \times 1.1^2 + \dfrac{1}{2}m_2\times 0^2$

KE₁ = 9.075 J

Kinetic energy after collision

$KE_2= \dfrac{1}{2}(15+4.5)\times 0.846^2$

KE₂ = 6.98 J

Change in KE = 6.98 - 9.075 = -2.096 J

hence,

mechanical energy was dissipated during this meal = -2.096 J

5 0

3 years ago

A wheel rolls purely on ground. If the velocity of a point 'P as shown on periphery of a body has a velocity equal

alexandr402 [8]

Answer:

(1) 120°

Explanation:

The wheel is purely rolling, which means it rotates about an axis through the point where it touches the ground (see Figure 11-6).

The net velocity at point P on the periphery, relative to the bottom of the wheel, is:

v = ωr

where r is the distance from the point at the bottom of the wheel to P (see diagram).

To find r, we need to use some geometry. From Inscribed Angle Theorem, we know the inscribed angle is half the arc angle. And from Thales' Theorem, we know an angle inscribed across a diameter is a right angle.

Therefore:

cos (θ/2) = r / (2R)

r = 2R cos (θ/2)

So the net velocity at P is:

v = 2Rω cos (θ/2)

We want this to equal the velocity at the center of the circle, which is Rω.

Rω = 2Rω cos (θ/2)

1 = 2 cos (θ/2)

cos (θ/2) = 1/2

θ/2 = 60°

θ = 120°