Assuming force is constant, how does the mass of an object affect its acceleration?

Well a simple way to investigate this is to use the formula 

Force = Mass x Acceleration 

so if force is constant   say 10 units
  
10 = mass x acceleration 

if the mass is 5 units  the acceleration is 2 units

if the mass is 1 unit the acceleration is 10 units 

if the mass is 1/2 units the acceleration is 20 units

so hopefully you can see a pattern occurring that you can generalise for your answer

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