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4 years ago

How can humans use the electromagnetic spectrum in everyday life?

1 answer:

8 0

-- look both ways before crossing the street (light)
-- listen to the weather report (radio waves)
-- make a cellphone call (radio waves)
-- watch the game on TV (radio waves)
-- heat up a hunk of meatloaf for a fast snack (microwaves)
-- stand in the sunshine to warm up (infrared radiation)
-- lie in the sun to work on your tan (ultraviolet radiation)
-- the dentist makes a new set of pix of your teeth (X-rays)

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Andrew pokes a marble, and the marble rolls down a ramp. The marble moves with speed. Which forces are acting on the marble in t

MissTica

Answer: Velocity, Gravity, and Momentum

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3 years ago

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Suppose oil spills from a ruptured tanker and spreads in a circular pattern. If the radius of the oil spill increases at a const

Dafna1 [17]

Answer:

$\frac{dA}{dt} = 188.5 m^2/s$

Explanation:

As we know that area of the circle at any instant of time is given as

$A = \pi r^2$

now in order to find the rate of change in area we will have

$\frac{dA}{dt} = 2\pi r\frac{dr}{dt}$

here we know that

rate of change of radius is given as

$\frac{dr}{dt}= 1 m/s$

radius of the circle is given as

$r = 30 m$

now we have

$\frac{dA}{dt} = 2\pi (30)(1)$

$\frac{dA}{dt} = 60\pi$

$\frac{dA}{dt} = 188.5 m^2/s$

8 0

4 years ago

What services can you expect from a personal trainer?

ludmilkaskok [199]

Answer:

You answered your own question, I'm confused about what you're asking for.

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3 years ago

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What is the wavelength of a 2.2 mhz ultrasound wave traveling through aluminum? assume that the speed of sound in aluminum is 51

Eva8 [605]

The frequency of a wave is equal to the linear speed divided the wavelength. so in equation form.
f = v / l
so the wavlength
l = v / f
where f is the frequency
v iss the linear speed
l is the wavelength

l = ( 5100 m/s ) / ( 2.2 Mhz ) ( 10^6 hz / 1 Mhz )
f = 0.0023 m
f = 2.3 mm

7 0

3 years ago

Suppose you design an apparatus in which a uniformly charged disk of radius R is to produce an electric field. The field magnitu

ANEK [815]

Answer:

The electric field will be decreased by 29%

Explanation:

The distance between point P from the distance z = 2.0 R

Inner radius = R/2

Outer raidus = R

Thus;

The electrical field due to disk is:

$\hat {K_a} = \dfrac{\sigma}{2 \varepsilon _o} \Big( 1 - \dfrac{z}{\sqrt{z^2+R_i^2}} \Big)$ )

$\implies \dfrac{\sigma}{2 \vaepsilon _o} \Big ( 1 - \dfrac{2.0 \ R}{\sqrt{ (2.0\ R)^2+(R)^2}} \Big)$

Similarly;

$\hat {K_b} = \hat {k_a} - \dfrac{\sigma}{2 \varepsilon_o} \Big( 1 - \dfrac{2.0 \ R}{\sqrt{(2.0 \ r)^2 + (\dfrac{R}{2}^2)}}\Big)$

However; the relative difference is: $\dfrac{\hat {k_a} - \hat {k_b}}{\hat {k_a} }= \dfrac{E_a -E_a + \dfrac{\sigma}{2 \varepsilon_o \Big[1 - \dfrac{2.0 \ R}{\sqrt{(2.0 \ R)^2 + (\dfrac{R}{2})^2}} \Big] } } { \dfrac{\sigma}{2 \varepsilon_o \Big [ 1 - \dfrac{2.0 \ R}{\sqrt{ (2.0 \ R)^2 + (R)^2}} \Big] }}$

$\dfrac{\hat {k_a} - \hat {k_b}}{\hat {k_a} }= \dfrac{1 - \dfrac{2.0}{\sqrt{(2.0)^2 + \dfrac{1}{4}}} }{1 - \dfrac{2.0 }{\sqrt{(2.0)^2 + 1}}}$

$= 0.2828 \\ \\ \mathbf{\simeq 29\%}$

3 0

3 years ago