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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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What distance will a vehicle travel before coming to a complete stop from a speed of 70 mph, (a) When the vehicle is traveling o

OLga [1]

Answer:

(a), The SSD will be 723.9 ft.

(b-1), The SSD will be 620.2 ft.

(b-2), The SSD will be $723.91>SSD>620.2$

(c), The SSD will be 910.5 ft.

Explanation:

Given that,

Speed = 70 mph

Suppose, a perception reaction time of 2.5 sec and the coefficient of friction is 0.35

We need to calculate the stopping sight distance

Using formula of SSD

$SSD=1.47\times v\times t+\dfrac{v^2}{30\times(f\pm g)}$

Where, v = speed of vehicle

t = perception reaction time

f = coefficient of friction

g = gradient of road

(a). If the gradient of road is zero.

Then, the stopping sight distance will be

$SSD=1.47\times 70\times 2.5+\dfrac{70^2}{30\times(0.35)}$

$SSD=723.9\ ft$

(b-1). If the gradient of road is 0.1

Then, the stopping sight distance will be

$SSD=1.47\times 70\times 2.5+\dfrac{70^2}{30\times(0.35+0.1)}$

$SSD=620.2\ ft$

(b-2). If the grade continuously decrease then the SSD will be increase.

But if the grade is increase then the SSD will be decrease and for flat grade the SSD will be more.

So, The SSD will be $723.91>SSD>620.2$

(c). When the vehicle is traveling downhill on a roadway of constant grade then the vehicle take will be more SSD

So, The SSD will be

$SSD=1.47\times 70\times 2.5+\dfrac{70^2}{30\times(0.35-0.1)}$

$SSD=910.5\ ft$

Hence, (a), The SSD will be 723.9 ft.

(b-1), The SSD will be 620.2 ft.

(b-2), The SSD will be $723.91>SSD>620.2$

(c), The SSD will be 910.5 ft.

7 0

3 years ago

The Nichrome wire is replaced by a wire of the same length and diameter, and same mobile electron density but with electron mobi

Marina CMI [18]

Answer:

The electric field inside the wire will remain the same or constant, while the drift velocity will by a factor of four.

Explanation:

Electron mobility, μ = $\frac{v_d}{E}$

where

$v_d$ = Drift velocity

E = Electric field

Given that the electric field strength = 1.48 V/m,

Therefore since the electric potential depends on the length of the wire and the attached potential difference, then when the electron mobility is increased 4 times the Electric field E will be the same but the drift velocity will increase four times. That is

4·μ = $\frac{4*v_d}{E}$

6 0

3 years ago

Read 2 more answers

A roller-coaster car has a mass of 1080 kg when fully loaded with passengers. As the car passes over the top of a circular hill

Dmitriy789 [7]

Answer:

(a): The normal force on the car from the track when the car's speed is v= 7.6 m/s is FN= -6696 N.

(b): The normal force on the car from the track when the car's speed is v= 17 m/s is FN= 8912.7 N.

Explanation:

m= 1080 kg

r= 16m

v1= 7.6 m/s

v2= 17 m/s

g= 9.81 m/s²

v1= w1*r

w1= v1/r

w1= 0.475 rad/s

ac1= w1² * r

ac1= 3.61 m/s²

FN= m * (ac1 - g)

FN= -6696 N (a)

-----------------------------------------------------

v2= w2*r

w2= v2/r

w2= 1.06 rad/s

ac2= w2² * r

ac2= 18.06 m/s²

FN= m * (ac2 - g)

FN= 8912.7 N (b)

4 0

3 years ago

The ______________ scale has a single “anchor” point at the triple point of water.

Marysya12 [62]

The "Temperature" scale has a single "anchor" point at the triple point of water.

In short, Your Answer would be "Temperature"

Hope this helps!

8 0

4 years ago

Read 2 more answers

Emily holds a banana of mass m over the edge of a bridge of height h. She drops the banana and it falls to the river below. Use

Sladkaya [172]

Answer:

The speed of the banana just before it hits the water is:

√(2 · g · h) = v

Explanation:

Hi there!

Before Emily throws the banana, its potential energy is:

PE = m · g · h

Where:

PE = potential energy.

m = mass of the banana.

g = acceleration of the banana due to gravity.

h = height of the bridge (distance from the bridge to the ground).

When the banana reaches the water, all its potential energy will have converted to kinetic energy. The equation for kinetic energy is as follows:

KE = 1/2 · m · v²

Where:

KE = kinetic energy.

m = mass of the banana.

v = speed.

Then, when the banana hits the water:

m · g · h = 1/2 · m · v²

multiply by 2 and divide by m both sides of the equation:

2 · g · h = v²

√(2 · g · h) = v

5 0

3 years ago