A hybrid vehicle's regenerative braking system transfers 450 kJ of useful chemical energy to its onboard battery pack while slowing down over a period of 6.0 seconds6.0\text{ seconds}6.0 seconds.
Figure 1 shows a diagram of the energy transfers involved in this process.
Explain why the useful chemical energy stored in the battery is different from the total kinetic energy lost by the wheels of the vehicle during regenerative braking.