If the near-point distance of the jeweler is 25.8 cm, and the focal length of the magnifying glass is 7.70 cm, find the angular magnification when the diamond is held 5.48 cm from the magnifying glass. Assume the magnifying glass is directly in front of the jeweler's eyes.

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