All categories

3 years ago

I need some help w/ this:

Physics

1 answer:

pochemuha3 years ago

5 0

Answer:

The velocity of the police car is, v = 17.798 m/s

Explanation:

Given data,

The actual frequency of the siren, f = 2010 Hz

The observed frequency of siren is, f' = 2120 Hz

The velocity of the observer, v' = 0 m/s

The velocity of the source, v = ?

The formula for Doppler effect,

$f'=\frac{(V+v')}{(V-v)}f$

Where,

V - velocity of sound waves in air.

$v=V-(V+v')\frac{f}{f'}$

Substituting the given values,

$v=343-(343+0)\frac{2010}{2120}$

v = 17.798 m/s

Hence, the velocity of the police car is, v = 17.798 m/s

You might be interested in

A car drives on a circular road of radius R. The distance driven by the car is given by = + [where a and b are constants, and t

pishuonlain [190]

Answer:

The question is incomplete, the complete question is "A car drives on a circular road of radius R. The distance driven by the car is given by d(t)= at^3+bt [where a and b are constants, and t in seconds will give d in meters]. In terms of a, b, and R, and when t = 3 seconds, find an expression for the magnitudes of (i) the tangential acceleration aTAN, and (ii) the radial acceleration aRAD3"

answers:

a. $18a m/s^{2}$

b. $a_{rad}=\frac{(27a +b)^{2}}{R}$

Explanation:

First let state the mathematical expression for the tangential acceleration and the radial acceleration.

a. tangential acceleration is express as

$a_{tan}=\frac{d|v|}{dt} \\$

since the distance is expressed as

$d=at^{3}+bt$

the derivative is the velocity, hence

$V(t)=\frac{dd(t)}{dt}\\V(t)=3at^{2}+b\\$

hence when we take the drivative of the velocity we arrive at

$a_{tan}=\frac{dv(t)}{dt}\\ a_{tan}=6at\\t=3 \\we have \\a_{tan}=18a m/s^2$

b. the expression for the radial acceleration is expressed as

$a_{rad}=\frac{v^{2}}{r}\\a_{rad}=\frac{(3at^{2} +b)^{2}}{R}\\t=3\\a_{rad}=\frac{(27a +b)^{2}}{R}$

4 0

3 years ago

In 11.8 s, 151 bullets strike and embed themselves in a wall. The bullets strike the wall perpendicularly. Each bullet has a mas

Aneli [31]

Answer:

a. ΔP/Δt = 42.6 N

b. F = 42.6 N

c. P = 142042.4 Pa = 1.42 KPa

Explanation:

First, we find the change in momentum of the bullets. For one bullet:

ΔP = m(Vf - Vi)

where,

ΔP = Change in Momentum = ?

m = mass of bullet = 5 x 10⁻³ kg

Vf = Final Speed = 1110 m/s

Vi = Initial Speed = 0 m/s (Since bullets are initially at rest)

Therefore,

ΔP = (3 x 10⁻³ kg)(1110 m/s - 0 m/s)

ΔP = 3.33 N.s

For 151 bullets:

ΔP = (151)(3.33 N.s)

ΔP = 502.83 N.s

Now, dividing this by time interval, Δt = 11.8 s

ΔP/Δt = 502.83 N.s/ 11.8 s

ΔP/Δt = 42.6 N

According to Newton's Second Law, the force is equal to rate of change of linear momentum:

Average Force = F = ΔP/Δt

F = 42.6 N

The pressure is given by:

Average Pressure = P = Average Force/Area

P = 42.6 N/ 3 x 10⁻⁴ m²

P = 142042.4 Pa = 1.42 KPa

4 0

3 years ago

4. Suppose the observed motion of a moving airplane, illustrated by a distance vs. time graph, is nearly a straight line with ze

jekas [21]

It shows that the airplane covers equal distance in equal time interval, that's it has a straight line from the origin.

The plane is moving at uniform speed.

7 0

3 years ago

What parts are found in an electric generator

Len [333]

Here are a list of items I found.

some brushes

a armature

a permanent magnet

some slip rings

3 0

3 years ago

Read 2 more answers

Waves with higher amplitude transfer ____energy.

natali 33 [55]

Answer:

- Waves with higher amplitude transfer HIGHER energy.

- Waves with higher frequency transfer HIGHER energy.

3 0

3 years ago