Can you please help me!!!

The capacitance of the variable capacitor of a radio can be changed from 100 to 350 pF by turning the dial from 0° to 180°. With

tangare [24]

Answer:

0.7 mJ

Explanation:

Identify the unknown:

The work required to turn the dial from 180° to 0°

List the Knowns:

Capacitance when the dial is set at 180°: C = 350 pF = 350 x 10^-12 F Capacitance when the dial is set at 0°: C = 100 pF = 100 x 10^-12 F

Voltage of the battery: V = 130 V

Set Up the Problem:

Energy stored in a capacitor:

U_c=1/2*V^2*C

=1/2*Q^2/C

When the dial is set at 180°:

U_c=1/2*(130)^2*350*10^-12=10^-4

Q=√2*U_c*C=4*10^-7

When the dial is set at 0°:

U_c=1/2*(4*10^-7)^2/100*10^-12

=8*10^-4 J

Solve the Problem:

ΔU_c=7*10^-4 J

=0.7 mJ

note:

there maybe error in calculation but method is correct

4 0

3 years ago

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The fed can attempt to decrease the federal funds rate by

Nataliya [291]

Answer:

purchasing bonds in order to increase the money supply.

Explanation:

The Federal Reserve raises or lowers interest rates through its regularly scheduled Federal Open Market Committee. That's the monetary policy arm of the Federal Reserve Banking System.

The Fed can attempt to increase the federal funds rate by selling Treasury bills, which decreases bank reserves.

4 0

3 years ago

A worker at the top of a 588-m-tall television transmitting tower accidentally drops a heavy tool. If air resistance is negligib

liq [111]

The final velocity of the tool is 107.4 m/s

Explanation:

We can solve this problem by using the principle of conservation of energy.

In fact, if air resistance is negligible, the total mechanical energy of the tool is conserved during the fall, so we can write:

$K_i + U_i = K_f + U_f$

where

$K_i = 0$ is the kinetic energy of the tool at the top (zero since it is at rest)

$U_i = mgh$ is the gravitational potential energy of the tool at the top, where

m is the mass of the tool

g is the acceleration of gravity

h is the heigth of the tool

$K_f = \frac{1}{2}mv^2$ is the kinetic energy of the tool just before hitting the ground, where

v is the final speed of the tool

$U_f = 0$ is the gravitational potential energy of the tool at the bottom (zero since the height is zero)

Re-arranging the equation,

$mgh=\frac{1}{2}mv^2$

where we have

$g=9.8 m/s^2\\h=588 m$

And solving for v,

$v=\sqrt{2gh}=\sqrt{2(9.8)(588)}=107.4 m/s$

Learn more about kinetic energy and potential energy:

brainly.com/question/6536722

brainly.com/question/1198647

brainly.com/question/10770261

#LearnwithBrainly

3 0

3 years ago

Is this spring or winter?

Nikolay [14]

Answer:

Spring

Explanation:

3 0

3 years ago

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Explain why a city with the same latitude but higher elevation will have a lower temperature

dezoksy [38]

The higher the altitude the less molecules in the air.

5 0

4 years ago