Chapter 20 - Electric Potential and Electric Potential Energy - Problems and Conceptual Exercises - Page 722: 98

$-7.220\times 10^4V$

We know that $\Delta V=\frac{m(g-a)\Delta d}{q}$ We plug in the known values to obtain: $\Delta V=\frac{(0.250Kg)(6.5637m/s^2-4.32525m/s^2)(1m)}{7.75\times 10^{-6}C}$ $\Delta V=7.220\times 10^4V$ As $\Delta V=V_f-V_i$ $\implies V_i=V_f-\Delta V$ We plug in the known values to obtain: $V_i=0V-7.220\times 10^{4}V$ $\implies V_i=-7.220\times 10^4V$