Physics

20 Examples of Newton’s first law

Sir. Isaac Newton proposed three laws in 1867 that describe the relationship between force and motion. These laws set up the basis for classical physics. Newton’s first law of motion explains the impact of force on the state of motion of an object. Newton’s first law is also known as the law of inertia. This article discusses 20 examples of Newton’s first law of motion.

Newton’s first law statement

We can state Newton’s first law as:

An object in rest or uniform motion in a straight line will continue to be in rest or uniform motion unless and until acted upon by an external force.

This law shows that all objects have a tendency to maintain their original state of motion. An external force is necessary for causing a change in speed, direction, or state of motion. The resistance to this external force is called inertia.

Newton’s first law of motion examples

Passengers swinging in a turning bus
A rock at rest
An astronaut moving continually in space
Skidding off roads while taking a turn
A marathon runner is unable to stop after the finish line
A cycle moving even after peddling is stopped
The sudden application of breaks in a vehicle
The change of direction of a soccer ball
The change of direction of a baseball
Taking a walk
Getting down from a moving vehicle
The dusting of a carpet
A vehicle moving immediately from a state of rest
Swimming
the rolling ball coming to a stop
Jumping in a trampoline
the revolution of planets in a solar system
Revolution of electrons in an atom
The reaction force from the ground
Rockets escaping the Earth’s gravity
Earthquake

Let us discuss each examples of Newton’s first law and see how they are consistent with Newton’s first law of motion.

20 Examples of Newton’s first law:

Passengers swinging in a turning bus:

Whenever a bus turns sharply, we can feel ourselves moving in the opposite direction. This is in accordance with Newton’s first law which states that a body moving in a straight line continues to move in a straight line unless acted by an external force. So your body is trying to move in the original direction, but the force of the bus is moving you in the other direction. This is called the inertia of direction.

A rock at rest:

A rock that is lying on the ground will continue to do so for thousands of years unless it is pushed by nature or by some force. It won’t be floating around in different places.

An astronaut moving continually in space:

In outer space, there is no force of gravity. So an object in motion continues to be in motion because there is no external force to stop its motion. Astronauts are able to fly due to this reason, which is in accordance with Newton’s first law.

Skidding off roads while taking a turn:

While taking a turn, we are deviating from a straight-line path. This causes the inertia of direction. Our body continues to move in a straight line, but the vehicle tries to turn. This causes the vehicle to be caught in the situation in which the vehicle skids. Centripetal force is very vital for turning. A centripetal force is an example of an external force that according to Newton’s first law of motion causes a change in direction. Centripetal force can be provided by the banking of roads or increasing frictional force.

The sudden application of breaks in a vehicle:

When a driver applies breaks all of a sudden, we tend to move forward. The vehicle stops due to the brakes. But we are in motion due to inertia. That is why seat belts are very important for road safety. You will understand more by seeing this animation.

A marathon runner unable to stop after the finish line:

A marathon is a competition in which the runners run for very long distances. When they approach the finish line they don’t stop immediately. They continue to run for a short distance to continue with the inertia of motion. Since their body was in motion, it was very difficult to bring it to rest in a moment.

A cycle moving even after peddling is stopped:

A cycle is able to move only when we peddle using the muscular force of our legs. But, when we stop peddling while we are in motion, the cycle moves on its own without any application of force. This is an example of inertia of motion according to Newton’s first law which states that a body in motion continues to be moved unless stopped by an external force. The external force here is friction, which, after some time, stops the motion of the cycle.

The change of direction of a baseball:

In a game of baseball, a baseball is hit by a bat. The muscular force is transferred to the ball via the bat which changes the direction and speed of motion of the ball.

Taking a walk:

Before we start to walk (or take a step), we are ideally in a state of rest. So there is an external force required for our motion according to Newton’s first law. The external forces that act here are our muscular force and the frictional force. While we walk we push the ground with the help of friction and get a motion in the forward direction. You can learn more about this in our post on friction as a necessary evil.

Getting down from a moving vehicle:

While we get down from a vehicle, our body is in motion due to the inertia of motion. But, the moment we step on the ground, the lower part of our body comes to a rest, but the inertia of motion will cause the body to move in a forwarding direction, thus causing us to fall in the direction of the motion of the vehicle.

The dusting of a carpet:

While we dust a carpet, the carpet is set in motion, but the dust particle is at rest due to the inertia of rest. Thus, the dust particles get separated from the carpet.

A vehicle moving immediately from a state of rest:

While sitting in a stationary vehicle our body is in a state of rest and will be in such a state unless acted upon by an external force. When it starts immediately, the vehicle moves but our body tends to lean back to the original position due to the inertia of rest.

The change of direction of a soccer ball:

In a game of soccer, the soccer ball is continuously kicked around this is another example of Newton’s first law. According to Newton’s first law of motion, it should be in motion forever, but it is stopped by external forces namely friction and muscular force. Frictional force stops the ball from moving forever. The muscular force can stop, or change the direction or speed of the soccer ball.

Example of newtons first law showing the effect of force — Example of newton’s first law: Application of force in a game of soccer

Swimming:

We can float in water without moving for a long time. But for motion, we need to apply muscular force by our hands and legs to push the water backward and propel ahead.

The rolling ball coming to a stop:

A rolling ball should roll forever according to Newton’s first law of motion. But the external force of rolling friction stops it from rolling forever.

Jumping in a trampoline:

When we jump in a trampoline we are thrown skywards but eventually, we do come down. This is due to the force of gravity which acts as the external force to bring us back. In this example of Newton’s first law, the gravitational force acts as an external force.

The revolution of planets in a solar system:

In outer space, there is not much effect of gravity for humans. But larger objects like planets experience gravitational force from the sun. This is a force that keeps the solar system in place.

Revolution of electrons in an atom: This example is similar to the revolution of planets around the sun. The electrons are negatively charged and move around a positively charged nuclease due to the electrostatic force of attraction. If this external force was absent then the electron would have flown off.

The reaction force from the ground:

A body in motion should be in motion unless acted by an external force. When Earth’s gravitational force pulls us into the center of the Earth we should be pulled into the center of the Earth. But, the reaction force provided by the ground stops us from being pulled into the center. This example of newton’s first law is a bit difficult to understand. You can experience it by jumping on the ground and seeing how you come to a stop. It is only when you hit the ground that you come to a stop.

Rockets escaping the Earth’s gravity:

Rockets have to escape the gravitational pull of the earth in order to enter outer space. In outer space, there is no force acting on the rockets so they can move unhindered. But to escape the Earth’s gravitational pull they move at a very high speed called the escape velocity.

Earthquake:

When an earthquake occurs, all things, including massive buildings, are thrown into motion. This is an example of the inertia of motion. The objects are in a state of rest and will try to remain at rest due to Newton’s first law. But, when the Earth below is set into motion due to the collision of tectonic plates, the objects try to remain at rest and hence fall down.

20 Examples of Newton’s first law

Table of Contents

Newton’s first law statement

Newton’s first law of motion examples