Aristotelian and Galilean Concepts of Motion

Motion

• Motion is the action of changing location or position.
• Life involves motion, including bodily movements and heart pumping.

Aristotelian Concept of Motion

1. Vertical Motion

• Natural motion; objects return to their natural state based on composition (earth, water, air, fire).
• Example: A ball falls back down after being thrown up because its natural element is earth.

2. Horizontal Motion

• Requires external force (push or pull) to maintain.
• Example: Boxes remain on the floor until pushed.
• Classified as "violent motion" (not harmful).

3. Projectile Motion

• Believed to be parallel to the ground until it stops falling.
• Heavy objects fall faster than light ones; movement ceases when force is forgotten.

Galilean Concept of Motion

1. Vertical Motion

• Absence of resistance means objects fall regardless of weight, determined by fall time.
• Example: A 1 kg object and a 10 kg object fall at the same rate.

2. Horizontal Motion

• A body in motion continues in motion unless impeded.
• Example: A ball pushed on a flat plane continues rolling if unimpeded.

3. Projectile Motion

• Identified uniformly accelerated motion. Projectile paths are parabolic.
• Galileo established a distinction between horizontal uniform motion and vertical acceleration.

Key Differences Between Aristotle and Galileo

• Aristotle: Emphasized natural and violent motion, thought mass influenced fall rates.
• Galileo: Introduced empirical methods, observed uniform acceleration, and defined mass independence.

Newton's Laws of Motion

First Law:

• Objects in motion remain in motion and objects at rest remain at rest unless acted on by an external force (Law of Inertia).

Second Law:

• Force equals mass times acceleration (F = ma).

Third Law:

• For every action, there is an equal and opposite reaction.