k=

To find kinetic energy, we use the following formula:
k = 
where k represents kinetic energy (measured in joules), m is the object's mass (in kg), and v signifies the object's velocity (in m/s). For cart A, we denote the mass as
and the velocity as
translating to the kinetic energy of cart A. Hence,
= 
For cart B, we define the mass as
and the velocity as 2v leading to the kinetic energy of cart B. Thus,

=

= 2

Considering that both carts are the same, it follows they possess identical mass, i.e.,
=
= m. Therefore, the total kinetic energy K comprises the sum of the kinetic energies of cart A and cart B.