An airplane flying due north at 90km/h is being blown due west at 50 km/h. What is the magnitude of the resultant velocity of th
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To solve this problem we will apply the concepts related to the Doppler effect. The Doppler effect is the change in the perceived frequency of any wave movement when the emitter, or focus of waves, and the receiver, or observer, move relative to each other. Mathematically it can be described as
Here,
=frequency received by detector
=frequency of wave emitted by source
=velocity of detector
=velocity of source
v=velocity of sound wave
Replacing we have that,
Therefore the frequencty that will hear the passengers is 422Hz
As per the question the mass of two falling sky drivers is 132 kg.
First we have to calculate their acceleration.
Whenever a body falls freely under gravity,its acceleration is acceleration due to gravity i.e g whose value is 9.8 m/s^2.
The earth pulls the object with a force equal to the weight of the body.
Hence the force gravity F=W= mg [ here m is mass of the body]
Here m =132 kg.
Hence force of gravity F= mg
=132 kg ×9.8 m/s^2
=1293.6 kg m/s^2
=1293.6 N [ here N[newton] is the unit of force.]
As per the question the air resistance is one fourth of weight of the bodies.
Hence air resistance F' =1/4 mg
Here F acts in vertically downward direction while F' acts in vertically upward direction.
Hence the net force acting on the particle is F-F'.
From Newton's second law of motion we know that net force is the product of mass and acceleration i.e
[Here a is the acceleration]
In the second question it has been told that they descend with uniform speed.hence acceleration of the two bodies will be zero.
we know that F= ma
=m×0
=0 N
Hence they will not get any force when they will descend with a uniform speed.