Final answer:
Static friction is present when a trolley is pulled on a steel track, acting in the opposite direction to prevent slipping. It is influenced by the normal force and the coefficient of static friction.
Step-by-step explanation:
When a trolley with steel wheels is placed on a steel track and pulled, there is indeed static friction involved. The direction of the static friction is opposite the direction in which the trolley wheels would slip without it. Thus, if the trolley is pulled forward, the static friction acts in the backward direction at the point of contact. This frictional force allows the wheels to roll without slipping.
Several factors influence static friction between the trolley wheels and the track. These include the normal force, which is related to the weight of the load on the trolley, and the coefficient of static friction between steel wheels and the steel track.
The normal force is the perpendicular force exerted by the surface (in this case, the track) against the weight of the trolley. The coefficient of static friction is a dimensionless value that represents the frictional properties of the two materials in contact—steel on steel here.