You need to estimate the floor area of your unusual oval-shaped living room from memory. You remember that it is longer than it is wider, and is about 6 m long. So you take it to be rectangular with a width of 0.5 m and multiply width by length to get an estimate of 3 m2 . Why was your estimate not done correctly? The estimate ignored the space occupied by the furniture. The floor was not really rectangular. The assumed width was unrealistic. The area of a rectangle is not simply its length multiplied by its width.

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