3. Electric cars are being rapidly developed to replace gasoline powered cars, but the problem is not easy because it is hard to find as good a way as gasoline for storing and transporting energy. a. How much chemical energy in Joules are in 15 gallons of gasoline?
b. The energy capacity of batteries, such as used in the Tesla cars, are given in kW hrs. Their standard battery is 7.0 kW hrs and the cost is a substantial fraction of the price of the car. What capacity would a battery have to be equal to the energy in 15 gallons of gas?

Suppose that two tanks, 1 and 2, each with a large opening at the top, contain different liquids. a small hole is made in the side of each tank at the same depth 1.57 m below the liquid surface, but the hole in tank 2 has 2.49 times the cross-sectional area of the hole in tank 1. (a) what is the ratio ρ1/ρ2 of the densities of the liquids if the mass flow rate is the same for the two holes? (b) what is the ratio rv1/rv2 of the volume flow rates from the two tanks? (c) at one instant, the liquid in tank 1 is 14.9 cm above the hole. if the tanks are to have equal volume flow rates, what height above the hole must the liquid in tank 2 be just then?

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?

Acapacitor is storing energy of 3 joules with a voltage of 50 volts across its terminals. a second identical capacitor of the same value is storing energy of 1 joule. what is the voltage across the terminals of the second capacitor?