A client wants to know how well their refrigerator is operating. You placed 2.15kg of water at 21.5 degrees Celsius into the refrigerator’s freezing compartment. You measure that it takes 2 hours to freeze all the water into ice at its freezing point. Calculate at what rate (in joules per second) the refrigerator is removing heat from the freezer compartment.

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