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3 years ago

Why does the frequency of a siren get higher as an ambulance using that siren gets closer?

2 answers:

7 0

The answer is D. As the ambulance gets closer, the sound waves are compressed relative to the person; so the frequency increases.

yarga [219]3 years ago

7 0

I would say that the answer is D)

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Suzy drops a rock from the roof of her house. Mary sees the rock pass her 2.9 m tall window in 0.134 sec. From how high above th

timama [110]

Answer:

Explanation:

Given

length of window $h=2.9\ m$

time Frame for which rock can be seen is $\Delta t=0.134\ s$

Suppose h is height above which rock is dropped

Time taken to cover $h+2.9 is t_1$

so using equation of motion

$y=ut+\frac{1}{2}at^2$

where y=displacement

u=initial velocity

a=acceleration

t=time

time taken to travel h is

$h=0+0.5\times g\times (t_2)^2---2$

Subtract 1 and 2 we get

$2.9=0.5g(t_1^2-t_2^2)$

$5.8=g(t_1+t_2)(t_1-t_2))$

and from equation $t_1-t_2=0.134\ s$

so $t_1+t_2=\frac{5.8}{9.8\times 0.134}$

$t_1+t_2=4.416\ s$

and $t_1=t_2+\Delta t$

so $t_2+\Delta t+t_2=4.416$

$2t_2+0.134=4.416$

$t_2=0.5\times 4.282$

$t_2=2.141\ s$

substitute the value of $t_2$ in equation 2

$h=0.5\times 9.8\times (2.141)^2$

$h=22.46\ m$

8 0

3 years ago

A car generator turns at 400 rpm (revolutions per minute) when the engine is idling. It has a rectangular coil with 300 turns of

Sav [38]

The field strength needed to produce a 24.0 V peak emf is 0.73T.

To find the answer, we need to know about the expression of emf.

What's the expression of peak emf produced in a rotating rectangular loops?

The peak emf produced in a rotating loops= N×B×A×w
N= no. of turns of the loop, B= magnetic field, A= area of loop and w= angular frequency
So, B = emf/(N×A×w)

<h3>What's the magnetic field applied to the loop, when rectangular coil with 300 turns of dimensions 5.00 cm by 5.22 cm rotates at 400 rpm produce a 24.0 V peak emf?</h3>

N= 300, A= 5cm × 5.22cm = 0.05m × 0.0522m = 0.00261 m²
Emf= 24V, w= 2π×400 rpm= 2π×(400rps/60) = 42 rad/s
Now, B= 24/(300×0.00261×42)

B= 24/(300×0.00261×42) = 0.73T

Thus, we can conclude that the magnetic field is 0.73T.

Learn more about the electromagnetic force here:

brainly.com/question/13745767

#SPJ4

6 0

2 years ago

What happens to energy and frequency of a wave if its wavelength increases?

Dahasolnce [82]

Answer:

Waves can be measured using wavelength and frequency. ... The distance from one crest to the next is called a wavelength (λ). The number of complete wavelengths in a given unit of time is called frequency (f). As a wavelength increases in size, its frequency and energy (E) decrease.

7 0

3 years ago

Water that is moving across Earth’s surface is called

Vanyuwa [196]

Answer:

I'm pretty sure the answer is runoff

5 0

3 years ago

Read 2 more answers

What is the lift (in newtons) due to Bernoulli's principle on a wing of area 76 m2 if the air passes over the top and bottom sur

AveGali [126]

Answer: