In which position is it winter in North America? * 10 points
The model shows Earth in several positions relative to the sun.
3
2
North America
Equator
Position 1 because North America receives the most direct Sun
Position 2 because North America is tilted towards the Sun
Position 3 because North America is parallel to the Sun
Position 4 because North America is tilted away from the Sun

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