At the end of the action potentials depolarization, the membrane potential is about _ mv?

Apulley system is used to lift a 2,000 newton engine up a distance of 3 meters. the operator must apply a force of 250 newtons to the chain of the pulley system to lift the motor. to lift the engine 3 meters, the operator must pull a total of 30 meters of chain through the pulley system. what is the value of di?

The voltage applied across a given parallel-plate capacitor is doubled. how is the energy stored in the capacitor affected?

How do i solve this physics problem?