Answer:
it should be changes in velocity 
Explanation:
 I hope this helps! 
 
        
             
        
        
        
In an alpha decay, the original nucleus decays into a daughter nucleus + an alpha particle, which consists of 2 protons and 2 neutrons.
The atomic number (number of protons) of the Francium is 87, and since in the decay it loses 2 protons, the atomic number of the daughter nucleus should be 85. Looking at the periodic table ,this corresponds to Astatine, and therefore this is the element produced in the alpha decay of Francium-221.
Moreover, the mass number (number of protons+neutrons) decreases by 4 (because an alpha particle carries 2 protons+2 neutrons), therefore in the reaction the mass number will decrease from 221 to 217. 
So, the daughter element is astatine-217.
        
                    
             
        
        
        
Answer:
The magnitude of the electric field at distance r from the point charge q is 
Explanation:
Suppose, Find E(r), the magnitude of the electric field at distance r from the point charge q.
We know that,
The electric field is proportional to the point charge and inversely proportional to the square of the distance from the charge point .
In mathematically,

Where, q = charge point
R = distance from charge point
Hence, The magnitude of the electric field at distance r from the point charge q is 
 
        
             
        
        
        
a=363.593m/s*2   we have rectangular component of force so we first find force resultant by square both component then square root and finally divide with 0.2 kg mass
 
        
             
        
        
        
Answer:
Explanation:
The man is moving on a circular path . The reaction of wall is providing centripetal force .so 
R = mv² / r 
Frictional force = μR where  μ is coefficient of friction 
= μ x mv² / r 
Frictional force = μ x mv² / r