Question

when a bus starts suddenly the passengers Standing On It leads backward in the bus it is an example of Newton's first law ,Newton's third law ,Newton's second law, law of conservation of momentum

Answer 1

when a bus starts suddenly the passengers Standing On It leads backward in the bus it is an example of Newton's first law of motion.

Answer 2

Hello dear!

$\underline\bold{Newton's\:first\:law\:of\:motion}$

Your examples comes under Newton's first law of motion.

Newton's first law of motion states that if a body is at rest then it will remain at rest and if a body is in motion it will remain to move in same direction with same speed unless acted upon by an external unbalanced force.

Although we name it Newton's law but initially it was Galileo who discovered this fact. In other word we can say that Newton stole Galileo's thoughts and put it in the form of a law.

When a bus starts suddenly, the passengers standing on it leads backwards because their legs being in close contact with the surface of bus moves forward immediately but the upper body due to inertia of rest tends to be in rest so leads backwards.

$\large\bold{Inertia\:is\:the\:inherent\:property\:of\:all\:objects}$

More info:
Inertia is of two types:
1. Inertia of motion― The inherent property of all body by which they continue to be in motion unless acted upon by any external unbalanced force.
2. Inertia of rest― The inherent property of all objects by which they tend to be in rest unless acted upon by an external unbalanced force.

Hope it would be enough!