Answer: V = 15 m/s
Explanation:
As  stationary speed gun emits a microwave beam at 2.10*10^10Hz. It reflects off a car and returns 1030 Hz higher. The observed frequency the car will be experiencing will be addition of the two frequency. That is,
F = 2.1 × 10^10 + 1030 = 2.100000103×10^10Hz
Using doppler effect formula 
F = C/ ( C - V) × f
Where 
F = observed frequency 
f = source frequency 
C = speed of light = 3×10^8
V = speed of the car
Substitute all the parameters into the formula 
2.100000103×10^10 = 3×10^8/(3×10^8 -V) × 2.1×10^10
2.100000103×10^10/2.1×10^10 = 3×108/(3×10^8 - V)
1.000000049 = 3×10^8/(3×10^8 - V)
Cross multiply 
300000014.7 - 1.000000049V = 3×10^8
Collect the like terms 
1.000000049V = 14.71429
Make V the subject of formula 
V = 14.71429/1.000000049
V = 14.7 m/s
The speed of the car is 15 m/s approximately 
 
        
             
        
        
        
<u>Answer</u>
3.7 Km south
<u>Explanation</u>
The definition of displacement is the distance traveled in a specific direction. It is the vector quantity. We add displacements like the way we add vectors. 
Taking the direction towards North to be positive (+1.7 Km), the distance towards south would be negative (-5.4 Km).
Now lets add the two values. 
(+1.7) + (-5.4) = 1.7 - 5.4
                     = - 3.7 Km      But negative was towards south.
∴ Answer = 3.7 Km south. 
 
        
             
        
        
        
Electrical generator which operates using a magnetic field. It is the beginning of modern dynamos.
        
             
        
        
        
Answer:
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