Why does the elevator in the supermarket keep the cart still?
According to the equilibrium condition of concurrent force mgsina... A =goFN=IzomgcosO substitution on the type. To obtain the o=tanO 0=arctan / XO0 is called the friction angle. It is shown that the size of an independent quality friction angle of 0, the largest and only two kinds of material between the static friction coefficient. That is to say, when the elevator tilt angle is less than 0 when the friction angle, put the multiple things no matter in the elevator, it will not slip. This is the slope of the self-locking. Trolleys and lift is the use of self-locking principle makes in the car no matter the multiple items are not slide down
When the elevator angle mouth is small, the object is stationary on the elevator, according to the concurrent force equilibrium condition mgsina={we know that the magnitude of static friction in 0 and the maximum static friction between. The maximum static friction size is proportional to the pressure, namely =o type for the static friction coefficient, a dynamic friction coefficient is slightly larger than the when the elevator angle. When Ot increases, the static friction force increases, as long as the <, objects will still remain stationary; when the angle of Ot is gradually increased to 0, the object began to exercise, the maximum static friction.
The phenomenon of self locking is that we can handle the cart with the goods as a whole. The object placed on the inclined elevator may slide along the inclined plane, or it may remain stationary
