# Newton’s first law

Newton’s first law, also referred to as the law of inertia, asserts that an object will persist in its state of rest or uniform motion in a straight line unless influenced by an external force. Put simply, in the absence of unbalanced forces, an object will either remain at rest or continue moving with a constant velocity.

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## Examples

### Bowling ball

Newton’s first law applies to objects, and this law indicates that they will remain at rest unless acted upon by an external force. This law can be observed in the case of a stationary bowling ball, which will not start moving towards the pins on its own. Instead, an external force, such as a person throwing or rolling the ball, is required to initiate its motion. This example highlights how Newton’s first law emphasizes the need for an external force to overcome the inertia of objects and set them in motion.

When a bowling ball is already in motion, Newton’s first law continues to hold true. According to this law, the ball will keep rolling unless acted upon by external forces that oppose its motion. Factors such as friction between the ball and the bowling lane or the collision with a bowling pin can serve as unbalanced forces that bring the ball to a stop. The opposing force exerted by these external forces counteracts the ball’s existing motion, eventually causing it to come to a stop. This example further exemplifies how Newton’s first law highlights the persistent nature of an object’s motion unless influenced by external factors.

### Bicycle

When a bicycle is at rest, it remains stationary until an external force is applied to set it in motion. This observation aligns with Newton’s first law of motion, which states that objects will maintain their state of rest or uniform motion in a straight line unless acted upon by an unbalanced force. In the case of a bicycle, the force required to initiate its movement comes from the rider applying force to the pedals. By exerting force with their legs, the rider overcomes the inertia of the stationary bicycle, and this enables it to accelerate and begin moving.

Once a bicycle is in motion, it will continue moving with a constant velocity unless acted upon by an external force. This observation is in line with Newton’s first law of motion, which states that objects in motion will persist in their motion until an external force alters their state. In the case of a moving bicycle, it means that the bicycle will not naturally come to a stop. To slow down or bring the bicycle to a halt, an external force is required. This force can be applied through mechanisms such as the friction between the brake pads and the wheel rims or the resistance encountered from the terrain. By exerting these opposing forces, the rider can decelerate and eventually stop the bicycle, thereby changing its state of motion as described by Newton’s first law.

### Billiard ball

The behavior of a billiard ball on a pool table exemplifies Newton’s first law of motion. While at rest, the ball will remain motionless until an external force is applied. In other words, it requires an outside influence, such as a strike from a pool cue, to set it in motion. This law emphasizes the concept of inertia, where the ball’s natural tendency is to stay at rest until acted upon by an unbalanced force.

Once a billiard ball is in motion, it will continue moving unless acted upon by an external force. Newton’s first law asserts that the ball will not cease its motion spontaneously. Instead, it will keep rolling until it encounters an opposing force, such as colliding with another ball or reaching the edge of the table. This law highlights the ball’s inherent tendency to maintain its current state of motion until influenced by an external factor.

### Car

When a car is parked and not in motion, it adheres to Newton’s first law of motion. The car will remain stationary unless an external force is applied. This means that the car will not start moving by itself. Instead, an external force, such as turning the ignition key or someone exerting a pushing force, is required to overcome its inertia and initiate its motion. Newton’s first law emphasizes the need for an external force to break the car’s state of rest and set it in motion.

When a car is in motion, Newton’s first law continues to hold true. This law states that an object in motion will continue moving at a constant velocity unless acted upon by an external force. In the context of a moving car, it means that the car will keep moving unless an unbalanced force is applied to alter its state of motion. The car will not come to a stop on its own; instead, an external force, such as applying the brakes, must be exerted to counteract its motion and bring it to a halt. Newton’s first law emphasizes that objects in motion tend to stay in motion until acted upon by an external force.

### Puck

Newton’s first law is exemplified when considering a stationary puck in the game of hockey. According to this law, an object at rest will remain at rest unless acted upon by an unbalanced force. In the case of the puck, it will not start moving by itself. Instead, it requires an external force, such as being struck by a player’s stick, to initiate its motion. This external force provides the necessary impetus to overcome the puck’s inertia and set it into motion across the ice.

Once the puck is in motion, it will continue moving until acted upon by an external force. Newton’s first law, also known as the law of inertia, states that an object in motion will persist in its state of motion unless an external force acts upon it. In the context of a moving hockey puck, this means that it will not spontaneously come to a stop. Instead, an unbalanced force is needed to halt its motion. This force can arise from various factors, such as the collision with another player’s stick or the resistance offered by the friction between the puck and the ice surface. These external forces counteract the puck’s motion, and this counteraction leads to a complete stop, as predicted by Newton’s first law.

### Scooter

Observing a stationary scooter parked on the road offers a clear demonstration of Newton’s first law in action. This fundamental law states that objects at rest will remain at rest unless acted upon by an external force. In the case of a stationary scooter, it will stay still until an external force, such as the rider starting the engine or applying a pushing force, disrupts its state of rest and initiates its motion.

When a scooter is in motion, it becomes apparent that it will continue moving forward unless an external force opposes its motion. This observation aligns with Newton’s first law of motion, which asserts that an object in motion will stay in motion unless acted upon by an external force. In the case of a moving scooter, the force of friction between the tires and the road, as well as the application of the brakes, serves as the unbalanced force that gradually slows down the scooter’s speed and eventually brings it to a stop. This example highlights Newton’s first law by illustrating how objects in motion tend to maintain their velocity unless acted upon by an external force.

### Tomato ketchup

Tomato ketchup trapped inside a bottle demonstrates Newton’s first law of motion. When the ketchup is at rest, it resists any change in its state and remains stationary. It requires an external force to set it in motion. For instance, tilting or squeezing the bottle applies an unbalanced force. This force overcomes the ketchup’s inertia, thereby allowing the ketchup to flow out. This demonstrates how Newton’s first law applies to objects like ketchup. They naturally resist changes in their state of motion, remaining at rest until an external force disrupts this state.