It is the first one. But if you have this question you are not a little boy
Answer:
the resistors In series have much power
The maximum is 1800 J since energy is not created nor destroyed, it is just transformed. In this example, gravitational potential energy is transformed to kinetic energy.
here we will use the momentum conservation
initial total momentum = final total momentum


now plug in all data here



so the final speed will be 7.94 m/s