7.5 X 10" C of charge. If the energy supplied could be converted entirely to kinetic energy, what speed would it give to a 1200-kg car? 13. . . IP BIO The Sodium Pump Living cells actively "pump" Se positive sodium ions (Na* ) from inside the cell to outside the 21. cell. This process is referred to as pumping because work must be done on the ions to move them from the negatively charged 22 inner surface of the membrane to the positively charged outer surface. Given that the electric potential is 0.070 V higher out- side the cell than inside the cell, and that the cell membrane is 0.10 um thick, (a) calculate the work that must be done (in 23 joules) to move one sodium ion from inside the cell to outside. (b) If the thickness of the cell membrane is increased, does your answer to part (a) increase, decrease, or stay the same. Ex- plain. (It is estimated that as much as 20% of the energy we consume in a resting state is used in operating this "sodium 24 pump.") 14. . . IP The electric potential of a system as a function of position along the x axis is given in Figure 20-24. (a) In which of the regions, 1, 2, 3, or 4, do you expect Ex to be greatest? In which 25