Physics: Motion, Forces, Energy, and Machines

Vocabulary terms covering position, motion, Newton's Laws, forms of energy, work, simple machines, and fluid dynamics based on the lecture transcript.

Reference Point

The starting point used to describe the location of an object, providing a frame of reference for determining position.

Position

An object's distance in a specific direction from a reference point; it requires distance, direction, and a reference point for a complete description.

Motion

The process of changing position relative to a reference point.

Distance

The path length traveled by an object.

Displacement

The change in an object's position.

Speed

The rate of change of position per unit of time, typically measured in units of $m/s$.

Constant speed

A consistent rate of motion over time.

Instantaneous speed

The speed of an object at a specific moment in time.

Average speed

Total distance traveled divided by total time.

Velocity

The speed and direction of motion, often represented as an arrow where length indicates speed.

Acceleration

The measure of the change in velocity over time, measured in units such as $m/s^2$. It occurs when speed, direction, or both change.

Force

A push or pull exerted on an object.

Contact Forces

Forces that occur when objects physically touch each other.

Noncontact Forces

Forces that act on objects without direct contact.

Gravity

An attractive force between objects that have mass.

Weight

A measure of the gravitational force acting on an object.

Friction

A force that resists motion between surfaces; types include static, sliding, and fluid friction.

Net Force

The combination of all forces acting on an object.

Newton’s First Law of Motion

An object at rest remains at rest, and an object in motion continues in uniform motion unless acted upon by a net external force.

Inertia

The property of matter that resists changes in motion.

Newton’s Second Law

States that acceleration equals the net force divided by mass, represented by the formula $F = ma$. Acceleration occurs in the direction of the net force.

Centripetal force

A force that acts on objects moving in curved paths, such as gravity acting on orbiting objects.

Newton’s Third Law of Motion

States that for every action, there is an equal and opposite reaction force acting on a different object.

Momentum

The measure of an object's resistance to change in motion, defined as the product of mass and velocity.

Law of Conservation of Momentum

The principle that the total momentum of a closed system remains constant unless external forces act upon it.

Energy

The fundamental ability to do work or cause changes in the physical state of objects or systems.

Kinetic energy

The energy possessed by an object due to its motion, calculated by the formula $ext{Kinetic energy} = 0.5 imes m imes v^2$.

Potential energy

Stored energy possessed by an object due to its position, condition, or composition.

Gravitational potential energy

Potential energy that arises from an object's position relative to a gravitational field, such as the Earth's surface.

Elastic potential energy

Potential energy stored in stretched or compressed objects, like springs or rubber bands.

Chemical potential energy

Potential energy stored in chemical bonds and released during chemical reactions.

Work (General Physics)

The transfer of energy from one system to another by the application of force.

Mechanical energy

The combination of kinetic energy and potential energy in an object or system.

Sound energy

Energy arising from vibrations in a medium that propagates through waves.

Thermal energy

Also known as heat, it results from the random motion of particles in matter.

Electrical energy

Energy involving the movement of charged particles, such as electrons.

Radiant energy

Energy carried through space by light and other electromagnetic waves.

Nuclear energy

Energy released from atomic nuclei during nuclear reactions.

The Law of Conservation of Energy

The principle stating that energy cannot be created or destroyed, only changed in form or transferred between systems.

Nonrenewable energy resources

Finite energy sources that deplete over time and are consumed faster than they can be replenished naturally, such as fossil fuels.

Renewable energy resources

Energy sources that are replenished naturally and offer sustainable alternatives, such as solar, wind, and hydroelectric energy.

Work (Mathematical)

The product of force and displacement in the direction of the force, calculated as $W = F imes d$. Verified as positive when force and displacement are in the same direction.

Power

The rate at which work is done or energy is transferred, calculated by P = rac{W}{t} and measured in watts ($W$).

Machine

Any device designed to simplify work by amplifying force, changing its direction, or modifying the distance over which it is applied.

Mechanical advantage (MA)

The ratio of output force to input force; MA > 1 indicates force amplification.

Efficiency

The measure of how effectively a machine converts input work into useful output work, calculated as $rac{ ext{Useful output work}}{ ext{Total input work}} imes 100$%.

Simple machine

A basic mechanical device, such as a lever or pulley, that provides a mechanical advantage with minimal input force.

Lever

A simple machine consisting of a rigid bar (lever arm), a fulcrum (pivot point), and input/output forces.

Wheel and Axle

A simple machine consisting of a large wheel attached to a smaller axle that rotate together to transmit torque or amplify force.

Inclined Plane

A sloped surface that allows a user to exert force over a longer distance to lift objects with less input force.

Compound machine

A combination of two or more simple machines working together to achieve a task.

Fluid

A substance that can flow and adapt to the shape of its container, including both liquids and gases.

Pressure

The force exerted per unit area on a surface, calculated as P = rac{F}{A} and measured in Pascals ($Pa$).

Atmospheric Pressure

The pressure exerted by the weight of the atmosphere, which decreases with elevation and is approximately $101,325,Pa$ at sea level.

Density

The mass per unit volume of a substance, calculated as ho = rac{m}{V} and measured in $g/cm^3$ or $kg/m^3$.