Lecture 10: Motion and Force Cartes

What were the two main classes of motion according to Aristotle?

Natural motion motion that is straight up or straight down and violent motion imposed motion resulting from an external push or pull

What did Galileo's experiments on inclined planes demonstrate about rolling balls?

Balls rolling down downward-sloping planes pick up speed, while balls rolling up upward-sloping planes lose speed.

What is Galileo's concept of inertia?

The property of things to resist changes in motion.

What is mass?

A measure of the amount of matter in an object and its inertia. Units are kilograms (kg).

What is weight?

The force of gravity acting on an object. Units are Newtons (N) or pounds (lb).

What is the difference between mass and volume?

Mass is the amount of matter an object contains, while volume is the amount of space an object occupies.

What is density?

A measure of how much mass occupies a given space, calculated as mass divided by volume (d = m/v). Units are kg/m³ or g/cm³.

What is a net force?

The combination of all forces that act on an object.

What does the equilibrium rule state?

Whenever the net force on an object is zero, the object is in mechanical equilibrium (expressed as ΣF = 0).

What is a support force (or normal force)?

An upward force that balances the weight of an object resting on a surface.

Can a moving object be in mechanical equilibrium?

Yes, if it moves at a steady speed in a straight line without any change in its motion (constant velocity).

What is friction?

A contact force between materials that acts in a direction opposite to the relative motion of the objects.

How is speed defined?

Distance covered per unit of time. Formula: speed = distance / time. Units: meters per second (m/s).

What is the difference between speed and velocity?

Speed is simply how fast an object is moving, whereas velocity is speed in a given direction (a vector quantity).

How is acceleration defined?

The rate at which velocity changes with time. Formula: acceleration = change in velocity / time interval. Units: m/s².

What is free fall?

Motion of an object under the influence of gravitational pull only, with no air resistance.

What is the approximate acceleration of an object in free fall near Earth's surface?

Approximately 10 meters per second squared (often denoted as g = 10 m/s²).

What formula is used to calculate the speed of an object in free fall starting from rest?

v = gt, where v is speed, g is acceleration due to gravity, and t is time.

What formula is used to calculate the distance fallen by an object in free fall starting from rest?

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