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3 years ago

11

Sonar is used to determine the speed of an object. A 38.0-kHz signal is sent out, and a 40.0-kHz signal is returned. If the spee

d of sound is 341 m/s, how fast is the object moving?

1 answer:

ANEK [815]3 years ago

7 0

Answer:

The velocity is $v = 8.743 \ m/s$

Explanation:

From the question we are told that

The frequency of the signal sent out is $f_s = 38.0 \ kHz = 38.0 *10^{3} \ Hz$

The frequency of the signal received is $f_r = 40.0 \ kHz = 40.0 *10^{3} \ Hz$

The speed of sound is $v_s = 341 \ m/s$

Generally the frequency of the sound received is mathematically represented as

$f_r = f_s [\frac{v_s + v}{v_s - v} ]$

where v is the velocity of the object

=> $40 *10^{3} = 38 *10^{3} * [\frac{341 + v}{341 - v} ]$

=> $1.05263 = \frac{341+v }{341-v}$

=> $358.94 - 1.05263v = 341 + v$

=> $17.947 = 2.05263 v$

=> $v = 8.743 \ m/s$

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slamgirl [31]

Answer:

Stay the same

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We see that the voltage is inversely proportional to the capacitance. We said that the capacitance has halved: therefore, the potential difference across the two plates will double:

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Now we can analyze the electric field between the plates of the capacitor, which is given by

$E=\frac{V}{d}$

we said that:

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therefore, the new electric field will be

$E'=\frac{2V}{2d}=\frac{V}{d}=E$

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3 years ago

When Bella pushes a box with a mass of 5.25 kilograms with a force of 15.75 newtons, it accelerates at a rate of 2.5 meters/seco

Mariana [72]

Sure !

Start with Newton's second law of motion:

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This formula is so useful, and so easy, that you really
should memorize it.

Now, watch:

The mass of the box is 5.25 kilograms, and the box is
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Net Force = (mass) x (acceleration)

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But hold up, hee haw, whoa ! Wait a second !
Bella is pushing with a force of 15.75 newtons, but the box
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What happened to the rest of Bella's force ? ?

==> Friction is pushing the box in the opposite direction,
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How much ?

(Bella's 15.75 newtons) minus (13.125 that the box feels)

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5 0

3 years ago

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Viewing moving objects from pond water under his microscope and named then animalcules

pogonyaev

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3 years ago

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Answer:

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3 years ago

A person is pushing a box. The net external force on the 60-kg box is stated to be 90 N. If the force of friction opposing the m

Tems11 [23]

Answer:

$b.1.5m/s^2$

Explanation:

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2 years ago