To develop this problem we will apply the concepts related to the Doppler effect. The frequency of sound perceive by observer changes from source emitting the sound. The frequency received by observer 
is more than the frequency emitted by the source. The expression to find the frequency received by the person is,
= Frequency of the source
= Speed of sound
= Speed of source
The velocity of the ambulance is
Replacing at the expression to frequency of observer we have,
Therefore the frequency receive by observer is 878Hz
A. Reduced greenhouse gas emissions.
The speed of the wave created by Linh in the spring by moving the other end right and left with a frequency of 2 Hz is 1m/s.
<h3>How to calculate speed of a wave?</h3>
The speed of a wave can be calculated by using the following formula:
Speed = Wavelength x Frequency
According to this question, Linh creates waves in the spring by moving the other end right and left with a frequency of 2 Hz. If wave crests are 0.5 m apart, the speed can be calculated as follows:
speed = 2Hz × 0.5m
speed = 1m/s
Therefore, the speed of the wave created by Linh in the spring by moving the other end right and left with a frequency of 2 Hz is 1m/s.
Learn more about speed at: brainly.com/question/10715783
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Angular momemtum : mass * tangential speed * distance to the center = 50*2.1*3.6=37800 J.s
Answer:
measure the vector diagram first
