Answer:
It is used in MRI because it does not damage cells 
Radio waves are used for space research because they have very long wavelengths
Explanation:
Many parts of the electromagnetic spectrum are applied in clinical diagnosis and treatment of illnesses. However, these highly ionizing radiation damage cells and its dosage must be carefully managed to avoid creating radiation related health problems for the patients.
Radio waves can be used in MRI without issues because the energy of the radiation is not sufficient to cause damage to cells but is sufficient to provide images for the sake of medical diagnosis.
Secondly, radio waves have long wavelength. This property is suitable for long range
 communication. Hence it can be used in space research
 
        
                    
             
        
        
        
Answer:
Explanation:
From A to B
distance traveled with velocity 
  in time 
 
 
from B to C
distance traveled is 0.5 d with 
  and 
  velocity for half-half time
 
divide 1 and 2 we get
 
 
Now average velocity is given by 
 
taking 
  common
 
 
  
 
        
             
        
        
        
Answer:
wendy can travel 147 km in 3 hr if the speed is costant