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A parallel-plate vacuum capacitor has 7.72 J of energy stored in it. The separation between the plates is 3.30 mm. If the separa

maxonik [38]

Answer

3.340J

Explanation;

Using the relation. Energy stored in capacitor = U = 7.72 J

U =(1/2)CV^2

C =(eo)A/d

C*d=(eo)A=constant

C2d2=C1d1

C2=C1d1/d2

The separation between the plates is 3.30mm . The separation is decreased to 1.45 mm.

Initial separation between the plates =d1= 3.30mm .

Final separation = d2 = 1.45 mm

(A) if the capacitor was disconnected from the potential source before the separation of the plates was changed, charge 'q' remains same

Energy=U =(1/2)q^2/C

U2C2 = U1C1

U2 =U1C1 /C2

U2 =U1d2/d1

Final energy = Uf = initial energy *d2/d1

Final energy = Uf =7.72*1.45/3.30

(A) Final energy = Uf = 3.340J

4 0

3 years ago

An AC generator has an output rms voltage of 100.0 V at a frequency of 42.0 Hz. If the generator is connected across a 45.0-mH i

Rus_ich [418]

Answer:

(a) 11.8692‬ ohm

(b) 12.447 A

(c) 17.6 A

Explanation:

a) inductive reactance Z = L Ω

= L x 2π x F

= 45.0 x 10⁻³ x 2(3.14) x 42

= 11.8692‬ ohm

b) rms current

= 100 / 8.034

= 12.447 A

c) maximum current in the circuit

= I eff x rac2

= 12.447 x 1.414

= 17.6 A

4 0

4 years ago

A football player, with a mass of 69.0 kg, slides on the ground after being knocked down. At the start of the slide, the player

White raven [17]

Answer:

(a) -472.305 J

(b) 1 m

Explanation:

(a)

Change in mechanical energy equals change in kinetic energy

Kinetic energy is given by $0.5mv^{2}$

Initial kinetic energy is $0.5\times 69\times 3.7^{2}=472.305 J$

Since he finally comes to rest, final kinetic energy is zero because the final velocity is zero

Change in kinetic energy is given by final kinetic energy- initial kinetic energy hence

0-472.305 J=-472.305 J

(b)

From fundamental kinematic equation

$v^{2}=u^{2}+2as$

Where v and u are final and initial velocities respectively, a is acceleration, s is distance

Making s the subject we obtain

$s=\frac {v^{2}-u^{2}}{-2a}$ but a=\mu g hence

$s=\frac {v^{2}-u^{2}}{-2\mu g}=\frac {0^{2}-3.7^{2}}{-2*0.7*9.81}=0.996796272\approx 1 m$

7 0

3 years ago

Why will interference occur

den301095 [7]

Two waves interfere when they run into each other.

The barrier reflects waves that run straight into it. It acts as a wave source and sends wave pulses back up the page towards the incoming waves.

Imagine a loose string tied to a wall. Someone sends two consecutive pulses along the string towards the wall. The first pulse gets reflected right away. It will travel backward towards the person holding the string. Along its way, it will run into the second pulse. The two pulses will interfere. The wall will make the reflected pulse out of phase with the second one. They will end up creating a destructive interference.

So is the case with the water waves running into the barrier. The barrier will send incoming waves back toward where they came from. Reflected waves interfere with incoming ones.

7 0

3 years ago

The figure above represents a stick of uniform density that is attached to a pivot at the right end and has equally spaced marks

zavuch27 [327]

Answer:

After 2.0s the angular momentum is $L= 2(4A+3B+2C+D)x$