Answer:
f'=5.58kHz
Explanation:
This is an example of the Doppler effect, the formula is:

Where f is the actual frequency,  is the observed frequency,
 is the observed frequency,  is the velocity of the sound waves,
 is the velocity of the sound waves,  the velocity of the observer (which is negative if the observer is moving away from the source)  and
 the velocity of the observer (which is negative if the observer is moving away from the source)  and  the velocity of the source  (which is negative if is moving towards the observer). For this problem:
 the velocity of the source  (which is negative if is moving towards the observer). For this problem:


 
        
             
        
        
        
Explanation:
To be accurate, it must be able to make measurements that are close to the actual value.
 
        
             
        
        
        
Answer:

Explanation:
A simple pendulum is a system consisting of a mass attached to a string, and oscillating in a periodic motion, back and forth, along an equilibrium position.
The period of a pendulum is the time it takes for the pendulum to complete one oscillation.
The period of a pendulum is given by the equation

where
L is the length of the pendulum
g is the acceleration due to gravity
From the formula, we see that the period of a pendulum does not depend on the mass.
Therefore, the only 2 factors affecting the period of a pendulum are:
- The length of the pendulum: the longer it is, the longer the period of oscillation
- The acceleration due to gravity: the greater it is, the shorter the period of the pendulum
 
        
             
        
        
        
Answer:
Red giant or super giant → very cool but very luminous
                                       → found in the upper right of the H-R diagram.
Main sequence →The majority of stars in our galaxy
                         → Sun, for example
                         → a very hot and very luminous star
White dwarfs → very hot but very dim
                      → not much larger in radius than earth   
Explanation:
Giant:
 When the stars run out of their fuel that is hydrogen for the nuclear fusion reactions then they convert into Giant stars.That's why they are very cool. Giant stars have the larger radius and luminosity then the main sequence stars.
Main Sequence:
Stars are called main sequence stars when their core temperature reaches up to 10 million kelvin and their start the nuclear fusion reactions of hydrogen into helium in the core of the star. That is why they are very hot and luminous. For example sun is known as to be in the stage of main sequence as the nuclear fusion reactions are happening in its core.
White dwarfs:
When the stars run out of their fuel then they shed the outer layer planetary nebula, the remaining core part that left behind is called as white dwarf. It's the most dense part as the most of the mass is concentrated in this part.
 
        
             
        
        
        
Answer:
The answer is the option a.
Explanation:
We know that magnetic force (Fm) is defined as
Fm = q (v x B)
Where q is a the value of the charge, v is the velocity of the charge and B is the value of the magnetic field.
"v x B" is defined as the cross product between the vectors velocity and magnetic field, and if the angle between them is thetha < 180°, then, the cross product is
v x B = vBsin (thetha)
So,
Fm = qvBsin (thetha)
And, in case in which v and B are parallel vectors, thetha is zero, and,
sin (thetha)=sin (0) = 0
So, Fm=0