When we are standing in a bus and the bus begins to move suddenly, we tend to fall backwards. This is in accordance with which of the following laws of motion?

Newton's First Law of Motion

When we are standing in a bus and the bus begins to move suddenly, we tend to fall backwards. This is because the sudden start of the bus brings motion to the bus as well as to our feet in contact with the floor of the bus. But the rest of our body opposes this motion because of its inertia.

Newton's first law of motion is stated as: An object remains in a state of rest or of uniform motion in a straight line unless compelled to change that state by an applied force.

The first law of motion is also known as the law of inertia.