Question

difference of kinetic force between a havy object and a light one

Answer 1

Let the mass of the light body = m kg ,  its velocity = v m/s.
Let the mass of the heavy body = M kg,   M > m , its velocity V m/s.
KE = (mv)²/ (2m)  =  (MV)²/(2M )
(mv)²/(MV)² = m/M   < 1        =>   mv < MV
The heavier body has higher momentum.
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2)  lighter body:  m kg and  velocity V m/s
heavier body :  2 m  and  velocity V/2 m/s
Their momentum is same.
But    KE :  1/2 m V²   :  1/2 (2m) (V/2)²
KE :    1 :  1/2
The lighter body has a higher KE
I hope you understand it.