Physics - Chapter 3 First Law of Motion

Net Force

The overall force acting on an object when all the individual forces are combined.

Equilibrium

A state where the net force acting on an object is zero, resulting in no change in motion.

Weight

The gravitational force acting on an object, calculated as W = mg (weight = mass x gravitational acceleration).

Mass vs. Volume

Mass is the quantity of matter in an object (measured in kilograms), while volume is the space an object occupies (measured in cubic centimeters, etc.).

Galileo's Experiments

Demonstrated that a moving object does not need continuous force to maintain its motion; showed that objects in motion can remain in motion if friction is negligible.

Historical Perspectives on Motion

Initially, objects were thought to only move when acted upon by a force, with views from Aristotle and later challenges from Copernicus and Galileo.

Conservation of Energy

In the context of motion, it refers to the principle that a ball rolling from one incline to another can reach nearly the same height, demonstrating energy conservation.

Isaac Newton

Formulated the three laws of motion and made significant contributions to calculus and gravitational theory.

Galileo Galilei

Pioneer of the scientific method; conducted experiments that challenged Aristotelian physics and supported the idea of inertia.

Aristotle

Ancient Greek philosopher whose views on motion dominated Western thought for centuries, stating that motion requires a force.

Copernicus

Proposed the heliocentric model of the universe, challenging the Earth-centered view and laying the groundwork for modern astronomy.

Albert Einstein

Developed the theory of relativity, which transformed the understanding of space, time, and motion.

James Clerk Maxwell

Made foundational contributions to the field of electromagnetism, describing how electric and magnetic fields interact.

Newton's Second Law of Motion

States that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass; commonly represented as F = ma (force = mass x acceleration).

Formula for Weight

Weight (W) can be calculated using the formula W = mg, where m is mass and g is gravitational acceleration (approximately 9.81 m/s² on Earth).

Formula for Kinetic Energy

The kinetic energy (KE) of an object is given by the formula KE = 1/2 mv², where m is mass and v is velocity.

Formula for Potential Energy

Gravitational potential energy (PE) is calculated using PE = mgh, where m is mass, g is gravitational acceleration, and h is height.

Formula for Work

Work (W) is defined as the product of force (F) and displacement (d) in the direction of the force: W = Fd cos(θ), where θ is the angle between the force and displacement.

Formula for Momentum

Momentum (p) is calculated as p = mv, where m is mass and v is velocity.

Formula for Conservation of Energy

In closed systems, total energy remains constant; can be expressed as KE_initial + PE_initial = KE_final + PE_final.

First Law of Motion

An object remains at rest or in uniform motion unless acted upon.

Force

An interaction that causes a change in motion.

Aristotle's View

Objects at rest require a force to move.

Natural Resting Place

The assumed state of objects without external forces.

Galileo's Contribution

Challenged the need for force to maintain motion.

Friction

Force opposing motion between touching surfaces.

Microscopic Irregularities

Surface imperfections causing friction.

Inclined Plane Experiment

Galileo's test showing motion dynamics on slopes.

Gravity

Force attracting objects toward Earth.

Constant Velocity

Uniform motion without acceleration or deceleration.

Motion Against Gravity

Movement opposing gravitational pull.

Motion with Gravity

Movement in the direction of gravitational pull.

Friction's Role

Necessary to maintain motion in real scenarios.

Height Attainment

Ball reaches similar height on opposing incline.

Distance Traveled

Ball rolls further on longer inclined planes.

Inertia

Resistance of an object to changes in motion.

Natural Tendency

Moving bodies continue in motion unless acted upon.

Horizontal Plane

Surface where only friction affects motion.

Galileo's Conclusion

Without friction, motion continues indefinitely.

Inclined Plane Dynamics

Different angles affect ball's speed and height.

Resting Nature

Objects do not naturally stop moving without friction.

Objects at Rest

Remain at rest until acted upon by a force.

Objects in Motion

Continue moving in a straight line indefinitely.

Force-Free Environment

Area where no external forces act on objects.

Mass

Amount of matter in an object, measured in kg.

Acceleration Formula

a = Fnet/m; relates force, mass, and acceleration.

Greater Mass

Requires more force to change motion state.

Mass vs Volume

Mass is not the same as volume.

NASA Videos

Educational resources illustrating Newton's laws.

Air Table

Surface providing nearly friction-free conditions.

Hockey Puck Example

Demonstrates effects of friction on motion.

Straight Line Motion

Path of an object without external forces.

Gravity's Role

Keeps planets in orbit around the sun.

Constant Speed

Motion at unchanging velocity in absence of forces.

Kick Test

Demonstrates inertia based on mass differences.

Empty Can vs Filled Can

Shows how mass affects motion resistance.

Nonzero Net Force

Required to change an object's state of motion.

Galileo's Idea

Force not needed to maintain motion.

STEMonstrations

Experiments illustrating principles of motion.

SI Unit of Force

Newton (N), equivalent to kg•m/s².

Gravitational Acceleration

9.81 m/s² on Earth's surface.

Mass vs Weight

Mass is constant; weight varies with gravity.

Proportional Relationship

Twice the mass equals twice the weight.

Volume

Space occupied by an object.

Density

Mass per unit volume of a substance.

Force-Free Region

Area with negligible gravitational influence.

Newton Definition

Force required to accelerate 1 kg at 1 m/s².

Mass Measurement

Typically measured in kilograms (kg).

Weight Measurement

Typically measured in newtons (N).

1 kg to N Conversion

1 kg weighs approximately 10 N on Earth.

Bananas vs Bread

2 kg of bananas occupies less volume than 1 kg of bread.

Law of Inertia

Objects remain in motion unless acted upon.

Copernicus' Theory

Proposed a moving Earth in the 16th century.

Inertia and Location

Inertia remains constant regardless of location.

Mass and Inertia Relationship

More mass means more inertia.

Weightlessness

Condition where gravitational force is negligible.

Mass Consistency

Mass remains unchanged in different gravitational fields.

Force Equation

F = mg, where m is mass and g is gravity.

Geocentric model

Earth-centered view of the universe.

Vertical motion

Movement in the up or down direction.

30 km/s

Speed of Earth's movement around the sun.

Objects move with Earth

All objects on Earth share its motion.

High-speed vehicle

A car, bus, or plane moving quickly.

Coin flip example

Demonstrates inertia in moving vehicles.

Gravity's effect

Only influences vertical motion of objects.

Perfect circle

Historical belief about Earth's orbital path.

Newton's laws

Fundamental principles governing motion and forces.

Aristotle's belief

Earth is stationary and at universe's center.

Galileo

First to challenge Aristotelian views scientifically.

Weight of matter

Force of gravity acting on an object's mass.

10 N force

Weight of 1 kg of matter on Earth.

Straight-line path

Motion without gravitational influence would be linear.

Air movement

Contributes to perceived motion of objects.

Wall's motion

Remains constant relative to a jumping person.

Natural motion

Historical view that Earth's motion is unnatural.

Center of the universe

Historical belief placing Earth in a central position.

Curved path

Trajectory of Earth if gravity were absent.

Assessment questions

Evaluate understanding of concepts discussed.

Catch a worm

Bird's action demonstrating motion relativity.