Answer:
A police car with its siren on is driving towards you, and you perceive the pitch of the siren to increase.
Explanation:
In Physics, Doppler effect can be defined as the change in frequency of a wave with respect to an observer in motion and moving relative to the source of the wave.
Simply stated, Doppler effect is the change in wave frequency as a result of the relative motion existing between a wave source and its observer.
The term "Doppler effect" was named after an Austrian mathematician and physicist known as Christian Johann Doppler while studying the starlight in relation to the movement of stars.
<em>The phenomenon of Doppler effects is generally applicable to both sound and light. </em>
An example of the Doppler effect is a police car with its siren on is driving towards you, and you perceive the pitch of the siren to increase. This is so because when a sound object moves towards you, its sound waves frequency increases, thereby causing a higher pitch. However, if the sound object is moving away from the observer, it's sound waves frequency decreases and thus resulting in a lower pitch.
<em>Other fields were the Doppler effects are applied are; astronomy, flow management, vibration measurement, radars, satellite communications etc. </em>
Answer:

Explanation:
As in any sample you will have 75.8% of Cl-35 iosotopes and 24.3% of Cl-37 iosotopes you can get the average atomic mass as:

<u>Answer:</u>
<em>Thunderbird is 995.157 meters behind the Mercedes</em>
<u>Explanation:</u>
It is given that all the cars were moving at a speed of 71 m/s when the driver of Thunderbird decided to take a pit stop and slows down for 250 m. She spent 5 seconds in the pit stop.
Here final velocity 
initial velocity
distance
Distance covered in the slowing down phase = 







The car is in the pit stop for 5s 
After restart it accelerates for 350 m to reach the earlier velocity 71 m/s





total time= 
Distance covered by the Mercedes Benz during this time is given by 
Distance covered by the Thunderbird during this time=
Difference between distance covered by the Mercedes and Thunderbird
= 
Thus the Mercedes is 995.157 m ahead of the Thunderbird.
Answer:
<h3>25km/hr</h3>
Explanation:
Velocity is the change in displacement of a body with respect to time.
Velocity - Displacement/time
Given
displacement = 76km
Time = 3hours
Substitute the given parameters into the formula;
Velocity = 75km/3hrs
Velocity = 25km/hr
Hence the velocity of the narwhal is 25km/hr