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OLga [1]
3 years ago
6

You are driving along a highway at 35.0 m/s when you hear the siren of a police car approaching you from behind and you perceive

the frequency as 1370 Hz. You are relieved that he is in pursuit of a different speeder when he continues past you, but now you perceive the frequency as 1330 Hz. What is the speed of the police car? The speed of sound in air is 343 m/s.
Physics
1 answer:
swat323 years ago
6 0

Answer:

Explanation:

Given

Apparent  frequency f'=1370\ Hz

Velocity of sound v=343\ m/s

speed of observer v_o=35\ m/s

Using Doppler effect Apparent frequency when source is approaching is given by

f'=f(\frac{v-v_0}{v-v_s})

1370=f(\frac{343-35}{343-v_s})---1

Apparent frequency when source moves away from observer

f''=f(\frac{v+v_0}{v+v_s})

1330=f(\frac{343+35}{343+v_s})---2

Divide 1 and 2 we get

\frac{f'}{f''}=\frac{\frac{343-35}{343-v_s}}{\frac{343+35}{343+v_s}}

\frac{1370}{1330}=\frac{343-35}{343-v_s}\times \frac{343+v_s}{343+35}

v_s=40\ m/s

Thus speed of sound of police car is 40 m/s

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For a curved mirror, all points have the same normal and the angle of incidence is also equal to the angle of reflection.

According to the laws of reflection, the incident ray, reflected ray and normal all lie on the same plane. For a curved mirror, the normal remains the same at all points along the curved mirror.

Again, the angle made between the incident ray and the normal is the same as the angle made between the reflected ray and the normal. Therefore, the angle of reflection is equal to the angle of incidence.

Learn more: brainly.com/question/17638582

8 0
2 years ago
If you have 80g of a radioactive substance whose half life is 2 days, how long will it take for the substance to decay to the po
Ber [7]

Answer:

6 days.

Explanation:

From radioactivity, The expression for half life is given as,

R/R' = 2⁽ᵃ/ᵇ)................... Equation 1

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Given: R = 80 g, R' = 10 g, b = 2 days.

Substitute into equation 1

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8 = 2⁽ᵃ/²⁾

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Equating the base and solving for a

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5 0
3 years ago
The magnetic field is 0.0 2M from the wire is 0.1 T what is the magnitude of the magnetic field 0.0 1M from the same wire
Kisachek [45]

Answer:

0.2 T

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4 0
3 years ago
Physics. Need help. Brainlieast answer for most/ all of the answers answered
Mumz [18]

<u>ALL of the following work assumes NO AIR RESISTANCE:</u>

1). an object moving under the influence of only gravity, and not in orbit;  its horizontal velocity is constant, and its vertical motion is accelerated downward at 9.8 m/s²

2). a parabola

3). Horizontal: velocity is constant, acceleration is zero. . . . Vertical: acceleration is 9.8 m/s² downward, velocity depends on whether it was launched, thrown up, thrown down, dropped, etc.

4). a). the one that was thrown horizontally; b). both  hit the ground at the same time; c). both hit the ground with the same vertical velocity

5). a). zero; b). zero; c). gravity ... 9.8 m/s² down; d). 3.06 seconds; e). 4.38 m/s; f). 30 m/s g). no; gravity has no effect on horizontal motion

6). a). 1.8 seconds;   b). 13.1 meters;   c). 17.6 m/s down;   d). 7.3 m/s; gravity has no effect on horizontal motion

7). 45 m/s

8). without air resistance, the ball is traveling horizontally at 13 km/hr, and it lands back in your hand

9). a). 4.49 m/s;  b). 29.7 m/s

10). 7.24 meters

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3 0
3 years ago
If your friend drops a chocolate bar to you from a height of 5.0 m above your hands,
Sladkaya [172]

Answer:

<h3>1.01 s</h3>

Explanation:

Using the equation of motion S = ut+1/2gt² to solve the problem where;

u is the initial velocity of the chocolate = 0m/s

t is the time taken

g is the acceleration due to gravity = 9.81m/s²

S is the height of fall = 5.0m

Substituting the given parameter into the formula to get the time t we have;

5 = 0(t)+1/2(9.81)t²

5 = 4.905t²

t² = 5/4.905

t² = 1.019

t = √1.019

t = 1.009 secs

<em>Hence it will take 1.01 secs for me to catch the chocolate bar</em>

6 0
3 years ago
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