Answer
See answers.
Work Step by Step
a. The stored energy is electrical potential energy.
$$PE=QV=(100A\cdot h)(\frac{C/s}{A})(3600s/h)(12V)\approx 4\times10^6J$$
b. The stored energy lets the wheelchair perform work: it applies a force to overcome the retarding force as it moves a distance d.
$$\Delta PE = Fd$$
$$d=\frac{\Delta PE}{F}=\frac{4.32\times10^6J }{210N}\approx 2\times10^4 m$$
