Several forces are applied to an object the object starts from rest moves a certain distance d then returns to rest which statement correctly describes the work done by the forces acting on the object a. The net work done by all the forces is zero
b. The net work done by conservative forces is zero
c. The net work done by the conservative forces is positive

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