Answer:
The shopping cart has less kinetic energy when it is empty.
Explanation:
When an object of mass [tex]m[/tex] travels at a speed of [tex]v[/tex], the kinetic energy of that object would be [tex](1/2)\, m\, v^{2}[/tex].
In this question, the speed of the shopping cart is fixed ([tex]v = 2\; {\rm m\cdot s^{-1}}[/tex].) Kinetic energy would be proportional to the mass [tex]m[/tex] of the shopping cart (including that of its contents.)
The mass of the shopping cart is lower when it is empty on the way back to the store. Therefore, the kinetic energy of the shopping cart would also be lower than when it was full.
