Question

Today's tallest buildings are really not that much taller than 12 the tallest buildings of the 1940 's. One big problem with making an even taller skyscraper ning the whole height of the building. So many elevators are needed to serve the building's shafts start taking up to0 much of the space within the building. An alternative is to have elevators that can move both horizontally and vertically: with such a design, many elevator cars can share a few shafts, and they don't get in each other's way too much because they can detour around each other. In this design, it becomes im- possible to hang the cars from cables, so they would instead have to ride on rails which they grab onto with wheels. Friction would keep them from slipping. The figure shows such a frictional elevator in its vertical travel mode. (The wheels on the bottom are for when it needs to switch to horizontal motion.) (a) If the coefficient of static friction between rubber and steel is s, and the maximum mass of the car plus how much force must there be pressing each wheel against the rail in order to keep the car from slipping? accelerating.) (b) Show that your result has physically reasonable behavior with is that every elevator needs its own shaft run- thousands of occupants that the elevator its passengers is M, (Assume the car is not In other words, if there was less friction, would the respect to wheels need to be pressed more firmly or less firmly? Does your equation behave that way? Ps.

Answer 1

ay from figure IN MAN 2 us N = mg ro b.) gl these is less friction than we have to press more firmly and you can see the same conclusion fosom result of (9) - N= mg e af value of is decreases than the Value of n will increase