Glossary
Big Idea #3: Force Interactions
A foundational concept in AP Physics 1 that explores how forces between objects lead to changes in their energy.
Example:
When you apply a force interaction to push a swing, you transfer energy to it, causing it to move higher.
Big Idea #4: Change
A core concept focusing on how energy is exchanged and transformed within or between systems, and how system choice affects energy storage and work.
Example:
Observing a roller coaster, you see its energy constantly undergoing change from potential to kinetic and back again.
Big Idea #5: Conservation
A fundamental principle stating that energy is transferred between objects or systems, but the total amount of energy in a closed system remains constant.
Example:
The principle of conservation means that even when a ball bounces, the total energy (kinetic, potential, and thermal from friction) remains the same.
Closed System
A system that allows energy exchange but not matter exchange with its surroundings.
Example:
A sealed thermos bottle containing hot coffee is a closed system; heat can eventually escape, but the coffee itself stays inside.
Conservation of Energy
A fundamental law stating that the total energy of an isolated system remains constant over time, though it may transform from one form to another.
Example:
In a frictionless roller coaster, the total mechanical energy (kinetic + potential) remains constant throughout the ride, demonstrating the conservation of energy.
Elastic Potential Energy (Usp)
Energy stored in a deformable elastic material, such as a spring, when it is stretched or compressed from its equilibrium position.
Example:
A compressed toy dart gun spring stores elastic potential energy that is converted to kinetic energy when the dart is fired.
Energy
The capacity to do work. It exists in various forms like kinetic, potential, and thermal.
Example:
A stretched rubber band has stored energy that can be released to launch a paper airplane.
Gravitational Potential Energy (Ug)
Energy stored in an object due to its position or height within a gravitational field relative to a reference point.
Example:
A diver standing on a high platform possesses significant gravitational potential energy before jumping.
Kinetic Energy (K)
The energy an object possesses due to its motion. It depends on the object's mass and speed.
Example:
A speeding bullet has a large amount of kinetic energy due to its high velocity.
Mechanical Energy
The sum of the kinetic energy and all forms of potential energy (gravitational, elastic) within a system.
Example:
A swinging pendulum's total mechanical energy remains constant if air resistance and friction at the pivot are negligible.
Open System
A system that allows both matter and energy to be exchanged with its surroundings.
Example:
A campfire is an open system because it exchanges heat (energy) and smoke (matter) with the environment.
Potential Energy (U)
Energy stored in an object due to its position or configuration, ready to be converted into other forms of energy.
Example:
A book resting on a high shelf has potential energy that can be converted to kinetic energy if it falls.
Power (P)
The rate at which work is done or energy is transferred. It measures how quickly energy is used or produced.
Example:
A powerful sports car has high power because it can do a lot of work (accelerate quickly) in a short amount of time.
Systems
Defined boundaries or collections of objects chosen for analysis in physics problems, which can be open or closed.
Example:
When analyzing a pendulum, you might define the pendulum bob and Earth as your system to study energy transformations.
Work (W)
The transfer of energy that occurs when a force causes a displacement of an object in the direction of the force. It is a scalar quantity.
Example:
Lifting a heavy box onto a shelf requires you to do work against gravity.
Work-Energy Principle
States that the net work done on an object is equal to the change in its kinetic energy.
Example:
If you push a stationary cart, the Work-Energy Principle tells you that the work you do directly translates into the cart's increased kinetic energy.