When Object is at zero height, and there is no potential energy possess by the object then it exerts Greatest Kinetic energy in it's whole Journey
Hope this helps!
        
             
        
        
        
In any case, your mass would be<em> 68 kg </em>no matter what
 
        
             
        
        
        
Answer:
a. the core will spin faster.
Explanation:
By law of conservation of angular momentum 
(mvR)i= (mvR)f
m= mass of star
v= speed of star
R= radius of star
i= initial 
f= final
since, size(R) of the star is reduced by factor of 10,000 and mass remains the same, the velocity must increase by the same factor to keep the angular momentum conserved. 
Hence, a. the core will spin faster.
 
        
             
        
        
        
Acceleration........................................
 
        
                    
             
        
        
        
Zero.
Acceleration is defined as the change in velocity over time.
Since in your case there is no change, there is no acceleration, so it is zero:
Or in formula: <span>a=<span><span>Δv</span>t</span></span>
Where a=acceleration, <span>Δv</span>=change in velocity and t=time