Physics: Momentum, Collisions, Impulse, and Head Injuries

Vocabulary practice flashcards covering linear momentum, open and closed systems, conservation of momentum, types of collisions, impulse, and the biomechanics and statistics of sports-related concussions.

Concussion

Brain damage caused by an impact to the head that accelerates the head rapidly, causing the brain to collide with the skull, change shape, and trigger chemical changes.

Momentum ($P$)

A vector quantity representing the product of an object's mass and its velocity ($P = m \times v$), measured in units of $kg\,m/s$.

Mass ($m$)

The measure of the amount of matter in an object, symbolized by $m$ and measured in kilograms ($kg$).

Velocity ($v$)

The speed and directional movement of an object, symbolized by $v$ and measured in meters per second ($m/s$).

Kilogram-meter per second ($kg\,m/s$)

The standard physical unit of measurement for momentum, calculated by multiplying mass in kilograms ($kg$) by velocity in meters per second ($m/s$).

Newton ($N$)

The standard unit of measurement used to quantify force ($F$) in momentum and impulse equations.

Second ($s$)

The standard unit of measurement for time ($t$) used in physics and impulse calculations.

Vector Quantity

A physical measurement that possesses both magnitude (size) and direction, such as momentum or velocity.

Positive Direction Convention

The directional sign convention in momentum problems assigning positive ($+$) values to motion oriented up, right, or forwards.

Negative Direction Convention

The directional sign convention in momentum problems assigning negative ($-$) values to motion oriented down, left, or backwards.

Momentum Formula

The equation $P = m \times v$, stating that momentum is calculated by multiplying an object's mass by its velocity.

Velocity Formula (from Momentum)

The rearranged momentum equation $v = \frac{P}{m}$, used to determine velocity given an object's momentum and mass.

Mass Formula (from Momentum)

The rearranged momentum equation $m = \frac{P}{v}$, used to determine an object's mass given its momentum and velocity.

Closed System

A system where no outside forces act on the objects, meaning all interacting forces and objects remain strictly within the system.

Conservation of Momentum

The principle stating that momentum cannot be created or destroyed, meaning the total momentum within a closed system remains constant ($\text{Initial Momentum} = \text{Final Momentum}$).

Hit and Stick Collision

A collision type where two separate moving objects collide and stick together to form a single combined object ($2\text{ objects become }1$).

Explosion Collision

A collision type where a single initial object separates or pushes apart into two distinct moving objects ($1\text{ object becomes }2$).

Bounce Off Collision

A collision type where two separate objects strike each other and bounce apart, remaining two distinct objects after the impact ($2\text{ objects become }2$).

Recoil

The backward movement and momentum experienced by an object (such as a cannon) when it forcefully expels another object (such as a cannonball) forward.

Open System

A system in which an object outside the designated system exerts an outside force on an object inside the system.

Outside Object

An object located outside the boundaries of a defined system that exerts an external force and alters the system's total momentum.

Impulse

A system's change in momentum caused by an outside force acting over an interval of time.

Impulse Formula

The equation $\text{Impulse} = F \times t$, which calculates the impulse by multiplying the outside force by the duration of impact.

Impulse Formula (Change in Momentum)

The equation $\text{Impulse} = \Delta P = P_f - P_i$, which calculates impulse by subtracting initial system momentum from final system momentum.

Positive Impulse

An impulse where an outside force acts into the system (depicted by an arrow pointing into the system circle), adding momentum to the system.

Negative Impulse

An impulse where an outside force acts against the system (depicted by an arrow pointing out of the system circle), subtracting momentum from the system.