Inertia. Newton’s First Law

21/07/2025

The online inertia simulations on this page help us to better understand the important concept of inertia in physics and its most significant implications.

The concept of inertia in physics

The concept of inertia in physics refers to a fundamental property of matter that consists of the tendency of objects to resist changes in their state of motion or rest. It is a central concept in physics and is related to Newton’s first law of motion, known as the law of inertia.

The concept of inertia. Newton’s first law or law of inertia

The law of inertia states that an object at rest tends to remain at rest, and an object in motion tends to maintain its velocity constant in a straight line unless an external force acts on it. This law is the basis of classical physics.

Inertia in physics. Applications in everyday life

Inertia manifests itself in various ways in everyday life. For example, when in an automobile and the driver brakes sharply, the occupants tend to continue moving forward because of their inertia. Similarly, when accelerating rapidly, the occupants are pushed backward because of their resistance to change from their resting state.

Inertia also explains why heavier objects require more force to move or stop than lighter objects. If a small object and a large object are pushed with the same force, the larger object will have a lower acceleration due to its greater inertia.

Explore the exciting STEM world with our free, online, simulations and accompanying companion courses! With them you’ll be able to experience and learn hands-on. Take this opportunity to immerse yourself in virtual experiences while advancing your education – awaken your scientific curiosity and discover all that the STEM world has to offer!

Inertia simulations

Elevator
Spacecraft

Motion of an elevator

In this simulation we can see what happens to the compression balance readings as the elevator moves up and down. What does this have to do with inertia in physics?

Inertia in a spacecraft

In this animation we can see that in space, where there is no friction, a spacecraft does not come to a screeching halt when it shuts down its engine. Instead, it keeps moving by inertia. What would you do to slow it down?

Horizontal
Vertical
Ball
Water
Elevator

Acceleration and deceleration

In this animation we have two blocks on top of a cart on a frictionless surface. When the cart starts, the block on the left falls to the ground. When the cart stops, it is the block on the right that falls. Explain these results from the concept of inertia in physics.

Uniform motion

In this animation, a cart with a block on it is moving at a constant speed. Suddenly the block is thrown vertically, while the cart continues its motion. Can you explain what happens? What would happen if the mass of the block or the velocity of the cart were changed?

Suspended ball

In this simulation we have a truck carrying a ball suspended by a cable. See what happens when accelerations or decelerations are applied to the truck and when the truck moves with uniform velocity. How does it relate to the concept of inertia in physics?

Water tank

In this simulation we have a truck carrying a tank of water. See what happens to the surface of the water when accelerations or decelerations are applied to the truck and when the truck moves with uniform velocity.

Motion of an elevator

In this simulation we can see what happens to the compression balance readings as the elevator moves up and down. What does this have to do with inertia in physics?

Giants of science

“If I have seen further, it is by standing on the shoulders of giants”

Isaac Newton

René Descartes

1596

–

1650

René Descartes developed analytic geometry and contributed to classical mechanics and the study of optics

“Pienso, luego existo”

Gaspard-Gustave de Coriolis

1792

–

1843

Gaspard-Gustave de Coriolis formulated the effect that bears his name, explaining the deflection of bodies on Earth’s rotation and providing key foundations for mechanics.

“Motion is not only trajectory, it is also invisible influence”