A current of 4 A flows from a battery when a light bulb is connected across its terminals. The p. d. across the terminals is 12V. a) What quantity of charge leaves the battery every second?
b) How much potential energy does each coulomb leaving the battery possess?
c) How much charge must be given out by the battery if it is to supply 60 joules of energy?
d) How long does the battery take to supply 60 joules of energy?

In an old-fashioned amusement park ride, passengers stand inside a 3.0-m-tall, 5.0-m-diameter hollow steel cylinder with their backs against the wall. the cylinder begins to rotate about a vertical axis. then the floor on which the passengers are standing suddenly drops away! if all goes well, the passengers will “stick” to the wall and not slide. clothing has a static coefficient of friction against steel in the range 0.60 to 1.0 and a kinetic coefficient in the range 0.40 to 0.70. part a what is the minimum rotational frequency, in rpm, for which the ride is safe? express your answer using two significant figures. f f = rpm