Physics Lournal

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Laws Of Motion

Inertia / Coasting

Why do skaters glide so effortlessly?

Inertia: Absent an external force, an object will continue moving as it is.

Friction, is the main inhibitor of inertia.

{{TODO}} Define friction. {{∆:1+0}}

Aristotle attempted to reason about inertia, thinking that velocity was proportional to external forces acting on an object, however this lead him to conclude that larger objects would fall faster than lighter ones, which is incorrect.

Five physical properties relating to motion:

Position: A specific point in space.

{{mermaid}}

graph TD

Position --> Direction

Position--> Distance

When we speak about position, it's always as a distance, and a direction, from some reference point (gauge).

Position is also known as a vector-quantity, meaning it has magnitude and direction.

Magnitude: How much of a quantity there is.

Direction: The orientation of a quantity (we assume cardinal here, but at some point Euclidean (x, y & z)).

Once you begin moving, another vector-quantity arises: Velocity.

Velocity: The rate at which a position is changing over time.

The magnitude, of an object's velocity, is what we commonly refer to as speed.

Speed: Distance traveled over a fixed amount of time.

Speed=distancetimeSpeed = \frac {distance} {time}.

Even if an object is motionless, it has a special velocity: 00, meaning it has no direction.

So, if it has no direction, is the velocity of a motionless object still a vector quantity?

Inertia, is commonly known as Newton's first law.

Acceleration

The reason speed and direction don't change during travel, is mass.

Mass is a scalar, meaning that it only has quantity, and can be considered as the measure of inertia.

This makes no sense to me at the moment..

Because of mass, inertial objects, will remain inertial, until subjected to external forces.

Force, is also a vector-quantity, having magnitude and direction.

Acceleration is the change in velocity resulting from external force(s) acting on an object.

Any change in velocity can be considered acceleration, even deceleration, which is just backwards acceleration.