Science 9: Newton's First Law and Inertia

Flashcards covering the concepts of inertia, friction, free body diagrams, and the historical perspectives of Aristotle, Galileo, and Newton on motion.

Inertia

The tendency for an object to stay at rest or in motion unless acted on by an unbalanced net force, or the inherent property of an object to resist changes in its motion.

Force

An influence that can change the motion or shape of an object.

Balanced Forces

Forces that result in a net force of zero ($0$), which is needed to keep an object at rest or moving at a constant speed.

Unbalanced Forces

Forces that result in a non-zero net force, which changes an object's state of motion.

Free Body Diagram (FBD)

A drawing that shows all the forces acting on an object, using arrows to represent the forces and a point or simple shape to represent the object.

Net Force

The total force acting on an object, found by combining all the forces while considering their direction.

Friction

A force that resists the motion of objects when they move or try to move over a surface.

Factors of Friction

The amount of friction depends on the roughness of the surfaces and the type of material; smoother surfaces have less friction, while rougher surfaces have more.

Aristotle

A Greek philosopher who believed a constant force was required to keep a moving object at a steady speed and that objects have a natural state of rest.

Galileo Galilei

The scientist who demolished the notion that a force is necessary to keep an object moving, arguing that an object can move freely in the absence of friction.

Isaac Newton

The scientist who discovered the laws of motion and universal gravitation, building on Galileo's observations to formalize the First Law of Motion.

Newton's First Law of Motion

Also known as the Law of Inertia, it states that an object at rest stays at rest, and an object in motion stays in motion at constant speed and direction unless acted upon by a net force.

Normal Force ($F_{N}$)

The upward support force exerted upon an object that is in contact with another stable object, such as a book on a table.

Gravitational Force ($F_{g}$)

The force of gravity (weight) acting downward on an object towards Earth.

Tension Force ($F_{t}$)

The force transmitted through a string, rope, or cable, such as the force acting on a picture frame on a wall.

Thrust ($F_{thrust}$)

A force that moves an aircraft forward.

Drag ($F_{drag}$)

A resistive force acting opposite to the motion of an object through a fluid, such as the air resistance encountered by an airplane.

Lift ($F_{L}$)

The upward force that opposes gravity and keeps an airplane in the air.