Question

Why is sand thrown on the tracks covered with snow?

Answer 1

When a person takes certain action for walking, the foot applies certain force i.e. Force of person in slanted direction which gives a backward horizontal component. Then the surface applies opposing frictional force F, which pushes people forward and enables them to walk.

Complete step by step solution:
When the roads (or tracks) are covered with snow then there is considerable reduction of frictional force between the tyres of the vehicle and the road (or between the track and the wheels of the train) which leads to the skidding of the vehicles. Thus, driving is not safe. When sand is thrown on the snow covered tracks or roads then the force of friction increases, so safe driving is possible.

Additional information:
Sand is a loose granular material that results from the disintegration of rocks, consists of particles smaller than gravel but coarser than silt, and is used in mortar, glass, abrasives, and foundry moulds. Snow is a precipitation in the form of small white ice crystals formed directly from the water vapour of the air at a temperature of less than$32^\circ F\left( {0^\circ C} \right)$ .

Note: Frictional force refers to the force generated by two surfaces that contact and slide against each other. A few factors that influence the friction force:
These forces are largely influenced by the texture of the surface and the amount of force that brings them together.
The object’s angle and orientation influence the amount of frictional force.
If an object is pushed against the surface, then the force of friction is enhanced and becomes greater than the object’s weight.