Physics: Energy, Work, Momentum, and Collisions

Vocabulary flashcards covering core physics concepts from Chapters 6 and 7, including momentum, impulse, elastic and inelastic collisions, work, power, conservative energy systems, and simple harmonic motion.

Inelastic Collision

A collision in which momentum is conserved, but kinetic energy is not conserved because energy is lost to deform the object or make the objects stick together.

Elastic Collision

A collision involving two objects bouncing off each other where both momentum and kinetic energy ($KE$) are conserved, resulting in two separate final velocities ($v_1'$ and $v_2'$).

Collision

Any interaction between objects that touch where force is involved ($F = ma$).

Momentum

The product of an object's mass and velocity, represented as $p = mv$ or $\Delta p = m\Delta v$, measured in units of $\text{Ns}$.

Impulse

What causes a change in momentum, defined by the formula $I = Ft$ and measured in units of $\text{Ns}$.

Impulse-Momentum Principle

The principle stating that the impulse acting on an object produces a change in momentum, expressed as $Ft = \Delta p$, $I = \Delta p$, or $I = m\Delta v$.

Recoil

A brief force between two objects causing them to move in opposite directions ($-p_1 = p_2$), where total momentum before is zero because no external force acts on either object.

Newton's Third Law (in Momentum)

The law stating that for every force there is an equal and opposite force, which directly leads to the principle of conservation of momentum.

Combined Velocity ($v'$)

The shared velocity of two objects during or after a collision when they stick together or do not have different final velocities, modeled by $m_1 v_1 + m_2 v_2 = (m_1 + m_2)v'$.

Conservative System

A system with no friction involved where mechanical energy is converted between potential and kinetic energy, remaining the same at every point.

Kinetic Energy

The energy of movement possessed by an object with velocity, given by the formula $KE = \frac{1}{2}mv^2$.

Gravitational Potential Energy

The energy of position possessed by an object due to its height, given by the formula $PE = mgh$.

Mechanical Energy

The total energy of an object ($E = KE + PE$), defined as the ability to perform work and move objects.

Conservation of Energy

The principle stating that total mechanical energy remains constant in a conservative system, expressed as $E_1 = E_2$ or $KE_1 + PE_1 = KE_2 + PE_2$.

Elastic Potential Energy

Energy stored in a spring, given by the equation $PE = \frac{1}{2}kx^2$, where $k$ is the spring constant in $\text{N/m}$ and $x$ is the distance compressed or stretched.

Simple Harmonic Motion

Repetitive back-and-forth motion over the $x$-axis that can be represented as a sine or cosine wave.

Equilibrium Point

The point where a spring naturally stretches with no net force, located at $x = 0\,\text{m}$.

Period ($T$)

The time needed for one complete cycle of motion, measured in seconds ($\text{s}$) and calculated as $T = \frac{1}{f}$.

Amplitude

The maximum distance an object moves from its equilibrium point.

Frequency ($f$)

The number of complete wavelengths or cycles that pass per second, measured in Hertz ($\text{Hz}$) and calculated as $f = \frac{1}{T}$.

Work

A scalar quantity describing the displacement of an object by a force acting along the same axis ($W = Fd$), measured in Joules ($\text{J}$).

Work Done by Friction

The negative work that opposes motion and decreases the available mechanical energy in a system.

Power

A measure of how quickly or efficiently work is performed on an object, calculated as $\text{Power} = \frac{\text{Work}}{\text{time}}$ and measured in Watts ($\text{W}$).

James Joule

A 19th-century English physicist, mathematician, and brewer who worked extensively in thermodynamics.

Emmy Noether

A German mathematician responsible for the fundamental development of energy theories.