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3 years ago

Jana lifted a 200-newton weight over her head to a distance of 2 meters above the ground. How much work did she do?

Physics

1 answer:

ira [324]3 years ago

4 0

Work = force * distance

force = 200 N
distance = 2m

Work = 200 * 2 = 400 J of work done.

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An 8.00- W resistor is dissipating 100 watts. What are the current through it and the difference of potential across it?

hjlf

Answer:

I= 3.5 amps

Explanation:

Step one:

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power P= 100W

Required

The current I

Step two

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substitute

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First of all, let's find the wavelength of the microwave. We have

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So the wavelength of the beam is

$\lambda=\frac{c}{f}=\frac{3\cdot 10^8 m/s}{12\cdot 10^9 Hz}=0.025 m$

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B) 0.23 W/m^2

First we calculate the area of the surface of the microwave at a distance of 30 km. Since the diameter of the circle is 750 m, the radius is

$r=\frac{750 m}{2}=375 m$

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The average intensity is

$I=\frac{P}{A}=\frac{1\cdot 10^5 W}{4.42\cdot 10^5 m^2}=0.23 W/m^2$

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