3. Living cells "pump" singly ionized sodium ions, Na+, from the inside of the cell to the outside across the membrane potential AVmembrane Vin - Vout= -70 mV. It is called pumping because work must be done to move a positive ion from the negative inside of the cell to the positive outside, and it must go on continuously because sodium ions "leak" back through the cell wall by diffusion. a. How much work must be done to move one sodium ion from the inside of the cell to the outside? b. At rest, the human body uses energy at the rate of approximately 100 W to maintain basic metabolic functions. It has been estimated that 20% of this energy is used to operate the sodium pumps of the body. Estimate to one significant figure the number of sodium ions pumped per second.

A 2000-kg electric car uses a 350-V battery pack. The car starts from rest and 4000 C flows from the battery. What's the maximum speed the car can reach during this time? Unload

Consider the circuit below. We have C1 = 10. pF, C2 = 20. pF, C3 = 30. pF, and V = 6.0 V. Answer the questions to follow regarding this circuit. i. What is the charge on C3? ii. What is the potential across C1? iii. What is the charge on C2? iv. What is the total energy stored in this system of capacitors?

5. Consider the circuit below. We have C₁ = 13 pF, C₂ = 20. pF, C3 = 30. pF, and V = 9.0 V. Answer the questions to follow regarding this circuit. i. What is the charge on C3? ii. What is the potential across C₁? iii. What is the charge on C₂? iv. What is the total energy stored in this system of capacitors? V C₁ C₂

Living cells "pump" singly ionized sodium ions, Na", from the inside of the cell to the outside to maintain a membrane potential AV membrane = Vin - Vout - 70 mV. It is called pumping because work must be done to move a positive ion from the negative inside of the cell to the positive outside, and it must go on continuously because sodium ions "leak" back through the cell wall by diffusion. a. How much work must be done to move one sodium ion from the inside of the cell to the outside? b. At rest, the human body uses energy at the rate of approxi- mately 100 W to maintain basic metabolic functions. It has been estimated that 20% of this energy is used to operate the sodium pumps of the body. Estimate-to one significant figure the number of sodium ions pumped per second.