You decide to take your middle school science class to the bowling alley for some “hands-on” experience with force and motion. You ask Jill to take a turn. After she releases the ball and it is
rolling down the alley, you ask her to describe the force(s) that are acting on the ball at that time.
Jill describes two forces:
1) The force of the ball moving forward down the alley, and
2) The force of friction that slows the ball down.
What aspects of her response, if any, are correct? What aspects of her response, if any, are
incorrect?

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