Scenario: It is 100 degrees F outside and the air-conditioner is keeping a house cool at 72 degrees F. If the door to the house is left opened what happens. A. The house will start to heat up because the cold air is leaving.

B. The house will start to heat up because the hot air is entering the house and the cold air is leaving.

C. The house will heat up heat up because the cold energy transferring outside and the warm energy is transferring inside.

D. The house will heat up because the heat energy from outside will transfer inside causing the house to get warm.

E. None of these answers are correct.

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