While developing his periodic table, dmitri mendeleev broke his own rule and placed the element tellurium before iodine in the group. he did this even though tellurium's atomic mass was known to be greater than iodine's. in his notes, mendeleev stated that he expected tellurium to have a lower atomic mass than iodine. however, all measurements continue to show that tellurium has a greater atomic mass than iodine even though tellurium acts like it has a lower atomic mass. what is the most likely reason that mendeleev placed tellurium before iodine?

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