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3 years ago

14

You want to create a device to warm food that is safe. Which type of electromagnetic wave would be most useful to investigate? A

) X–rays. B) infrared waves. C) gamma rays. D) ultraviolet waves

2 answers:

Liono4ka [1.6K]3 years ago

8 0

The best type of electromagnetic wave to use to warm food that is safe would be the infrared wave. The correct answer is B.

balandron [24]3 years ago

3 0

I think it is infrared because it is closer to microwave which is used to warm food

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A sinusoidal voltage is given by the expression ????(????)=20cos(5π×103 ????+60°) V. Determine its (a) frequency in hertz, (b) p

MA_775_DIABLO [31]

<em>There are some placeholders in the expression, but they can be safely assumed</em>

Answer:

(a) $f=1617.9\ Hz$

(b) $T=0.618\ ms$

(c) $A=20 \ Volts$

(d) $\varphi=60^o$

Explanation:

<u>Sinusoidal Waves </u>

An oscillating wave can be expressed as a sinusoidal function as follows

$V(t)&=A\cdot \sin(2\pi ft+\varphi )$

Where

$A=Amplitude$

$f=frequency$

$\varphi=Phase\ angle$

The voltage of the question is the sinusoid expression

$V(t)=20cos(5\pi\times 103t+60^o)$

(a) By comparing with the general formula we have

$f=5\pi\times 103=1617.9\ Hz$

$\boxed{f=1617.9\ Hz}$

(b) The period is the reciprocal of the frequency:

$\displaystyle T=\frac{1}{f}$

$\displaystyle T=\frac{1}{1617.9\ Hz}=0.000618\ sec$

Converting to milliseconds

$\boxed{T=0.618\ ms}$

(c) The amplitude is

$\boxed{A=20 \ Volts}$

(d) Phase angle:

$\boxed{\varphi=60^o}$

4 0

3 years ago

Define gravitational field

MariettaO [177]

"the field of force surrounding a body of finite mass in which anotherbody would experience an attractive force that is proportional to theproduct of the masses and inversely proportional to the square of thedistance between <span>them."

</span>

4 0

3 years ago

A car is designed to get its energy from a rotating flywheel with a radius of 1.50 m and a mass of 430 kg. Before a trip, the fl

fiasKO [112]

Answer:

a

$KE = 7.17 *10^{7} \ J$

b

$t = 6411.09 \ s$

Explanation:

From the question we are told that

The radius of the flywheel is $r = 1.50 \ m$

The mass of the flywheel is $m = 430 \ kg$

The rotational speed of the flywheel is $w = 5,200 \ rev/min = 5200 * \frac{2 \pi }{60} =544.61 \ rad/sec$

The power supplied by the motor is $P = 15.0 hp = 15 * 746 = 11190 \ W$

Generally the moment of inertia of the flywheel is mathematically represented as

$I = \frac{1}{2} mr^2$

substituting values

$I = \frac{1}{2} ( 430)(1.50)^2$

$I = 483.75 \ kgm^2$

The kinetic energy that is been stored is

$KE = \frac{1}{2} * I * w^2$

substituting values

$KE = \frac{1}{2} * 483.75 * (544.61)^2$

$KE = 7.17 *10^{7} \ J$

Generally power is mathematically represented as

$P = \frac{KE}{t}$

=> $t = \frac{KE}{P}$

substituting the value

$t = \frac{7.17 *10^{7}}{11190}$

$t = 6411.09 \ s$

3 0

3 years ago

6. several light bulbs are connected in series across a 115 v source

Natalka [10]

Explanation:

a) I = V / R

1.70 = 115 / R

R = 115 / 1.70

R = 67.647

R = 67.65 ohms

Therefore, equivalent resistance is 67.65 ohms

b) Equivalent resistance of circuit from above sum is 67.65 ohms

Given resistance of each bulb is 1.50 ohms

Number bulbs = Equivalent resistance / Resistance of each bulb

= 67.65 / 1.50

= 45

8 0

2 years ago

Please help if you have the time

Alex777 [14]

We know, length of segment wave is half the wavelength .

Let, wavelength of wave is $\lambda$ .

So, length of segment will be $\dfrac{\lambda}{2}$ .

Now, it is given that the string vibrates in four segments.

So,

$L = 4\times \dfrac{\lambda}{2}\\\\L = 2\lambda\\\\\lambda = 1\ m$

Speed can be given by :

$speed = wavelength \times frequency\\\\speed = 1\times 120\ m/s\\\\speed = 120\ m/s$

Therefore, the wave speed in the string is 120 m/s.

6 0

3 years ago