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Temka [501]
3 years ago
7

A car horn emits a frequency of 400 Hz. A car traveling at 20.0 m/s sounds the horn as it approaches a stationary pedestrian. Wh

at frequency does the pedestrian hear
Physics
1 answer:
Temka [501]3 years ago
8 0

Answer:

The observed frequency by the pedestrian is 424 Hz.

Explanation:

Given;

frequency of the source, Fs = 400 Hz

speed of the car as it approaches the stationary observer, Vs = 20 m/s

Based on Doppler effect, as the car the approaches the stationary observer, the observed frequency will be higher than the transmitted (source) frequency because of decrease in distance between the car and the observer.

The observed frequency is calculated as;

F_s = F_o [\frac{v}{v_s + v} ] \\\\

where;

F₀ is the observed frequency

v is the speed of sound in air = 340 m/s

F_s = F_o [\frac{v}{v_s + v} ] \\\\400 = F_o [\frac{340}{20 + 340} ] \\\\400 = F_o (0.9444) \\\\F_o = \frac{400}{0.9444} \\\\F_o = 423.55 \ Hz \\

F₀ ≅ 424 Hz.

Therefore, the observed frequency by the pedestrian is 424 Hz.

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Which four equations can be used to solve for acceleration
emmainna [20.7K]

The four equations for acceleration are obtained from the three equations of motion and from second law of motion.

Explanation:

Acceleration is defined as the rate of change of velocity with respect to time. So the change in velocity with respect to time can be determined using the three equations of motions.

So from the first equation of motion, v = u + at , we can determine the value of acceleration if time taken, final and initial velocity is known. The equation can be re-written as a = \frac{v-u}{t}

Similarly, from the second equation of motion, s = ut + 1/2 at², we can determine the equation for acceleration as a = 2*\frac{s-ut}{t^{2} }

So this is second equation for acceleration.

Then from the third equation of motion, v^{2}- u^{2} = 2* a *s

the acceleration equation is determined as a = \frac{v^{2}-u^{2}  }{2s}

In addition to these three equation, another equation is present to determine the acceleration with respect to force from the Newton's second law of motion. F = Mass × acceleration. From this, acceleration = Force/mass.

So, these are the four equations for acceleration.

8 0
3 years ago
How much force is needed to accelerate a 1,100 kg car at a rate of 1.5 m/s2?
Anna [14]
Assuming there is no force of friction...

F = ma
F = (1300kg)(1.5m/s^2)
F = 1950N
Just multiply mass by acceleration.
1300 x 1.5 = 1950N.
7 0
2 years ago
Correct Number Formats Numbers may be entered in several formats - including scientific notation and numerical expressions.
Illusion [34]

Answer:

a. Valid

b. Invalid

c. Invalid

d. Invalid

e. Valid

f.  Valid

g. Invalid

Explanation:

a.

Since, it follows all the four rules,

Therefore, this number is <u>Valid</u>

b.

It uses upper case E, instead of lower case e.

Therefore, it is <u>Invalid</u>

c.

It violates third rule for including unit.

Therefore, it is <u>Invalid</u>

d.

It violates the first rule. As, there is a space between 6 and e. While in the example given in question, there is no gap.

Therefore, it is <u>Invalid</u>

e.

Since, it follows all the four rules,

Therefore, this number is <u>Valid</u>

f.

Since, it follows all the four rules,

Therefore, this number is <u>Valid</u>

g.

It violates third rule for including unit.

Therefore, it is <u>Invalid</u>

6 0
3 years ago
A wire carrying a 29.0 A current passes between the poles of a strong magnet such that the wire is perpendicular to the magnet's
Dmitrij [34]

Answer:

2.59 T

Explanation:

Parameters given:

Current flowing through the wire, I = 29 A

Angle between the magnetic field and wire, θ = 90°

Magnetic force, F = 2.25 N

Length of wire, L = 3 cm = 0.03 m

The magnetic force, F, is related to the magnetic field, B, by the equation below:

F = I * L * B * sinθ

Inputting the given parameters:

2.25 = 29 * 0.03 * B * sin90

2.25 = 0.87 * B

=> B = 2.25/0.87

B = 2.59 T

The magnetic field strength between the poles is 2.59 T

4 0
3 years ago
Please help fast i need urgent
Sloan [31]
Is there more information ?
5 0
3 years ago
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