A 10 kg cart with a momentum of 10 kg• m/s hits a 20 kg cart at rest. Momentum is calculated by using
the formula p = mv, where m is the mass of an object and vis the velocity of an object.

Change in momentum formula

The change in momentum resulting from an external force is called the impulse (I=mv-mvo) and is related to the force applied through the Impulse-Momentum Theorem: I = F tc = mv - mvo . Here F is the external force applied and tc is the amount of time the force is in contact with the object.

A plain is a low-lying relatively flat land surface with a very gentle slope and minimum local relief. About 55% of the earth’s land surface is occupied by plains.

Important Points

Plain has been formed by the deposition of sediments brought down by rivers, some plains have also been formed by the action of the wind, moving ice and tectonic activities.

When plains are formed by glacial deposits, they are called Glacial or Drift Plains.

When plains are formed by the river deposits, they are called riverine or alluvial plains.

The depositions of sediments in a lake give rise to a Lacustrine Plain or Lake Plains. The Valley of Kashmir is an example of a lacustrine plain.

When the wind is the major agent of deposition, those plains are called Loess Plains.

Thus, we can conclude that the Drift Plain is formed due to the work of the glaciers.

  Additional Information

The economic significance of Plains-

Fertile soil: As they have a flat surface, the means of irrigation can be easily developed. That is why plains are called the ‘Food baskets of the world’.

The growth of industries: The rich agricultural resources, especially of alluvial plains, have helped in the growth of agro-based industries. Since the plains are thickly populated, plenty of labour is available for the intense cultivation and for supplying the workforce for the industries.

Expansion of means of transportation: The flat surface of plains ease the building of roads, airports and laying down railway lines.

Centres of civilizations: Plains are centres of many civilizations.

Setting up of cities and towns: Easy means of transportation on land and the growth of agriculture and industries in plains have resulted in the setting up and expansion of cities and towns.