Answer : The kinetic energy will be 24 J.
Explanation : Given,
Mass of marble = 3 kg
Velocity of a marble = 4 m/s
Formula used to calculate the kinetic energy is:

where,
K.E = kinetic energy
m = mass
v = velocity
Now putting all the given values in this formula, we get:


Therefore, the kinetic energy will be 24 J.