Answer:
0.5kg
Explanation:
Given parameters:
Speed of the object  = 12m/s
Kinetic energy  = 36J
Unknown:
Mass of the object  = ?
Solution:
Kinetic energy is the energy due to the motion of a body. It is mathematically expressed as;
   K.E = [tex]\frac{1}{2}[/tex] m v² Â
 Insert the parameters and solve;
  36  =  [tex]\frac{1}{2}[/tex] x m x 12²
   36  = 72m
    m  = 0.5kg